Expandable fusion device and method of installation thereof

ABSTRACT

The present invention provides an expandable fusion device capable of being installed inside an intervertebral disc space to maintain normal disc spacing and restore spinal stability, thereby facilitating an intervertebral fusion. In one embodiment, the fusion device includes a central ramp, a first endplate, and a second endplate, the central ramp capable of being moved in a first direction to move the first and second endplates outwardly and into an expanded configuration. The fusion device is capable of being deployed down an endoscopic tube.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation of U.S. patent application Ser. No.13/961,603, (now issued as U.S. Pat. No. 9,561,116) filed on Aug. 7,2013, titled Expandable Fusion Device and Method of InstallationThereof, filed on Aug. 7, 2013 (published as US 2014/0067071), which isa continuation-in-part of U.S. patent application Ser. No. 13/531,844,(now issued as U.S. Pat. No. 8,852,279) entitled “Expandable FusionDevice and Method of Installation Thereof,” filed on Jun. 25, 2012 (nowissued as U.S. Pat. No. 8,852,279), which is a continuation-in-part ofU.S. patent application Ser. No. 12/875,637, entitled “Expandable FusionDevice and Method of Installation Thereof,” filed on Sep. 3, 2010 (nowissued as U.S. Pat. No. 8,845,731), the entire disclosures of all ofwhich are herein incorporated by reference in their entireties.

FIELD OF THE INVENTION

The present invention relates to the apparatus and method for promotingan intervertebral fusion, and more particularly relates to an expandablefusion device capable of being inserted between adjacent vertebrae tofacilitate the fusion process.

BACKGROUND OF THE INVENTION

A common procedure for handling pain associated with intervertebraldiscs that have become degenerated due to various factors such as traumaor aging is the use of intervertebral fusion devices for fusing one ormore adjacent vertebral bodies. Generally, to fuse the adjacentvertebral bodies, the intervertebral disc is first partially or fullyremoved. An intervertebral fusion device is then typically insertedbetween neighboring vertebrae to maintain normal disc spacing andrestore spinal stability, thereby facilitating an intervertebral fusion.

There are a number of known conventional fusion devices andmethodologies in the art for accomplishing the intervertebral fusion.These include screw and rod arrangements, solid bone implants, andfusion devices which include a cage or other implant mechanism which,typically, is packed with bone and/or bone growth inducing substances.These devices are implanted between adjacent vertebral bodies in orderto fuse the vertebral bodies together, alleviating the associated pain.

However, there are drawbacks associated with the known conventionalfusion devices and methodologies. For example, present methods forinstalling a conventional fusion device often require that the adjacentvertebral bodies be distracted to restore a diseased disc space to itsnormal or healthy height prior to implantation of the fusion device. Inorder to maintain this height once the fusion device is inserted, thefusion device is usually dimensioned larger in height than the initialdistraction height. This difference in height can make it difficult fora surgeon to install the fusion device in the distracted intervertebralspace.

As such, there exists a need for a fusion device capable of beinginstalled inside an intervertebral disc space at a minimum to nodistraction height and for a fusion device that can maintain a normaldistance between adjacent vertebral bodies when implanted.

SUMMARY OF THE INVENTION

In an exemplary embodiment, the present invention provides an expandablefusion device capable of being installed inside an intervertebral discspace to maintain normal disc spacing and restore spinal stability,thereby facilitating an intervertebral fusion. In one embodiment, thefusion device includes a central ramp, a first endplate, and a secondendplate. The central ramp may be capable of moving in a first directionto push the first and second endplates outwardly and into an unexpandedconfiguration. The expandable fusion device may be capable of beingplaced into the disc space down an endoscopic tube and then expandedinto an expanded configuration.

Further areas of applicability of the present invention will becomeapparent from the detailed description provided hereinafter. It shouldbe understood that the detailed description and specific examples, whileindicating the preferred or exemplary embodiments of the invention, areintended for purposes of illustration only and are not intended to limitthe scope of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will become more fully understood from thedetailed description and the accompanying drawings, wherein:

FIG. 1 is a side view of an embodiment of an expandable fusion deviceshown between adjacent vertebrae according to the present invention;

FIG. 2 is a front perspective view of the expandable fusion device ofFIG. 1 shown in an unexpanded position in accordance with one embodimentof the present invention;

FIG. 3 is a front perspective view of the expandable fusion device ofFIG. 1 shown in an expanded position in accordance with one embodimentof the present invention;

FIG. 4 is a rear perspective view of the expandable fusion device ofFIG. 1 shown in an unexpanded position in accordance with one embodimentof the present invention;

FIG. 5 is a rear perspective view of the expandable fusion device ofFIG. 1 shown in an expanded position in accordance with one embodimentof the present invention;

FIG. 6 is a side view of the expandable fusion device of FIG. 1 shown inan unexpanded position in accordance with one embodiment of the presentinvention;

FIG. 7 is a side view of the expandable fusion device of FIG. 1 shown inan expanded position in accordance with one embodiment of the presentinvention;

FIG. 8 is a perspective view of the central ramp of the expandablefusion device of FIG. 1 in accordance with one embodiment of the presentinvention;

FIG. 9 is a perspective view of the driving ramp of the expandablefusion device of FIG. 1 in accordance with one embodiment of the presentinvention;

FIG. 10 is a perspective of an endplate of the expandable fusion deviceof FIG. 1 in accordance with one embodiment of the present invention;

FIG. 11 a perspective view showing placement of the first endplate of anembodiment of an expandable fusion device down an endoscopic tube andinto the disc space in accordance with one embodiment of the presentinvention;

FIG. 12 is a perspective view showing placement of the second endplateof the expandable fusion device down an endoscopic tube and into thedisc space in accordance with one embodiment of the present invention;

FIG. 13 is a perspective view showing placement of the central ramp ofthe expandable fusion device down an endoscopic tube and into the discspace in accordance with one embodiment of the present invention;

FIG. 14 is a perspective view showing expansion of the expandable fusiondevice in accordance with one embodiment of the present invention;

FIG. 15 is a side schematic view of the expandable fusion device of FIG.1 having different endplates;

FIG. 16 is a partial side schematic view of the expandable fusion deviceof FIG. 1 showing different modes of endplate expansion;

FIG. 17 is a side schematic view of the expandable fusion device of FIG.1 with artificial endplates shown between adjacent vertebrae;

FIG. 18 is a front perspective view of an alternative embodiment of anexpandable fusion device shown in an unexpanded position in accordancewith one embodiment of the present invention;

FIG. 19 is a front perspective view of the expandable fusion device ofFIG. 18 shown in an expanded position in accordance with one embodimentof the present invention;

FIG. 20 is a rear perspective view of the expandable fusion device ofFIG. 18 shown in an unexpanded position in accordance with oneembodiment of the present invention;

FIG. 21 is a rear perspective view of the expandable fusion device ofFIG. 18 shown in an expanded position in accordance with one embodimentof the present invention;

FIG. 22 is a side view of the expandable fusion device of FIG. 18 shownin an unexpanded position in accordance with one embodiment of thepresent invention;

FIG. 23 is a side view of the expandable fusion device of FIG. 18 shownin an expanded position in accordance with one embodiment of the presentinvention;

FIG. 24 is a perspective of an endplate of the expandable fusion deviceof FIG. 18 in accordance with one embodiment of the present invention;

FIG. 25 is a perspective view of the central ramp of the expandablefusion device of FIG. 18 in accordance with one embodiment of thepresent invention;

FIG. 26 is a side view of the central ramp of the expandable fusiondevice of FIG. 18 in accordance with one embodiment of the presentinvention;

FIG. 27 is a top view of the central ramp of the expandable fusiondevice of FIG. 18 in accordance with one embodiment of the presentinvention;

FIG. 28 a perspective view showing placement of the central ramp of theexpandable fusion device of FIG. 18 in accordance with one embodiment ofthe present invention;

FIG. 29 is a perspective view showing placement of the first endplate ofthe expandable fusion device of FIG. 18 in accordance with oneembodiment of the present invention;

FIG. 30 is a perspective view showing placement of the second endplateof the expandable fusion device of FIG. 18 in accordance with oneembodiment of the present invention;

FIG. 31 is a perspective view showing placement of the actuation memberof the expandable fusion device of FIG. 18 in accordance with oneembodiment of the present invention;

FIG. 32 is a perspective view showing expansion of the expandable fusiondevice of FIG. 18 in accordance with one embodiment of the presentinvention;

FIG. 33 is a front perspective view of an alternative embodiment of anexpandable fusion device shown in an unexpanded position in accordancewith one embodiment of the present invention;

FIG. 34 is a front perspective view of the expandable fusion device ofFIG. 33 shown in an expanded position in accordance with one embodimentof the present invention;

FIG. 35 is a rear perspective view of the expandable fusion device ofFIG. 33 shown in an unexpanded position in accordance with oneembodiment of the present invention;

FIG. 36 is a rear perspective view of the expandable fusion device ofFIG. 33 shown in an expanded position in accordance with one embodimentof the present invention;

FIG. 37 is a side cross-sectional view of the expandable fusion deviceof FIG. 33 shown in an unexpanded position in accordance with oneembodiment of the present invention;

FIG. 38 is a side cross-sectional view of the expandable fusion deviceof FIG. 33 shown in an expanded position in accordance with oneembodiment of the present invention;

FIG. 39 is a perspective of an endplate of the expandable fusion deviceof FIG. 33 in accordance with one embodiment of the present invention;

FIG. 40 is a rear perspective view of an alternative embodiment of anexpandable fusion device shown in an unexpanded position in accordancewith one embodiment of the present invention;

FIG. 41 is a rear perspective view of the expandable fusion device ofFIG. 40 shown in a partially expanded position in accordance with oneembodiment of the present invention;

FIG. 42 is a rear perspective view of the expandable fusion device ofFIG. 40 shown in an expanded position in accordance with one embodimentof the present invention;

FIG. 43 is a side exploded view of the expandable fusion device of FIG.40 in accordance with one embodiment of the present invention;

FIG. 44 is a side cross-sectional view of the expandable fusion deviceof FIG. 40 shown in an unexpanded position in accordance with oneembodiment of the present invention;

FIG. 45 is a perspective view of an endplate of the expandable fusiondevice of FIG. 40 in accordance with one embodiment of the presentinvention;

FIG. 46 is a perspective view of the central ramp of the expandablefusion device of FIG. 40 in accordance with one embodiment of thepresent invention;

FIGS. 47-49 are perspective views of the driving ramp of the expandablefusion device of FIG. 40 in accordance with one embodiment of thepresent invention;

FIG. 50 is a rear perspective view of an alternative embodiment of anexpandable fusion device shown in an expanded position in accordancewith one embodiment of the present invention;

FIG. 51 is a side cross-sectional view of the expandable fusion deviceof FIG. 50 shown in an expanded position in accordance with oneembodiment of the present invention;

FIG. 52 is an exploded view of the expandable fusion device of FIG. 50in accordance with one embodiment of the present invention;

FIG. 53 is a top view of the expandable fusion device of FIG. 50 shownin an unexpanded position in accordance with one embodiment of thepresent invention;

FIG. 54 is a read end view of the expandable fusion device of FIG. 50shown in an expanded position in accordance with one embodiment of thepresent invention;

FIG. 55 is a perspective view of an endplate of the expandable fusiondevice of FIG. 50 in accordance with one embodiment of the presentinvention;

FIG. 56 is a perspective of a central ramp of the expandable fusiondevice of FIG. 50 in accordance with one embodiment of the presentinvention;

FIG. 57 is a perspective view of a driving ramp of the expandable fusiondevice of FIG. 50 in accordance with one embodiment of the presentinvention;

FIG. 58 is an exploded view of an alternative embodiment of anexpandable fusion device in accordance with one embodiment of thepresent invention;

FIG. 59 is a rear perspective view of the expandable fusion device ofFIG. 58 in an unexpanded position in accordance with one embodiment ofthe present invention;

FIG. 60 is a rear perspective view of the expandable fusion device ofFIG. 58 in an expanded position in accordance with one embodiment of thepresent invention;

FIG. 61 is a side cross-sectional view of the expandable fusion deviceof FIG. 58 in an unexpanded position in accordance with one embodimentof the present invention;

FIG. 62 is a side cross-sectional view of the expandable fusion deviceof FIG. 58 in an expanded position in accordance with one embodiment ofthe present invention;

FIG. 63 is a top view of the expandable fusion device of FIG. 58 in anunexpanded position in accordance with one embodiment of the presentinvention;

FIG. 64 is an exploded view of an alternative embodiment of anexpandable fusion device in accordance with one embodiment of thepresent invention;

FIG. 65 is a side cross-sectional view of the expandable fusion deviceof FIG. 63 in an unexpanded position in accordance with one embodimentof the present invention;

FIG. 66 is a side cross-sectional view of the expandable fusion deviceof FIG. 64 in an expanded position in accordance with one embodiment ofthe present invention;

FIG. 67 is an exploded view of an alternative embodiment of anexpandable fusion device in accordance with one embodiment of thepresent invention;

FIG. 68 illustrates dilator in accordance with embodiments of thepresent invention; and

FIGS. 69-73 illustrate cannula in accordance with embodiments of thepresent invention.

FIG. 74 is an exploded view of an alternative embodiment of anexpandable fusion device with a graft delivery hole in accordance withembodiments of the present invention;

FIGS. 75A and 75B are rear views of the expandable fusion device of FIG.74;

FIG. 76 is a top view of the expandable fusion device of FIG. 74;

FIG. 77 is a side view of the expandable fusion device of FIG. 74;

FIG. 78 is an exploded view of an alternative embodiment of anexpandable fusion device having removably attachable plates inaccordance with embodiments of the present invention;

FIG. 79 is a side view of the expandable fusion device of FIG. 78;

FIG. 80 is a perspective view of the expandable fusion device of FIG.78;

FIG. 81 is a rear view of the expandable fusion device of FIG. 78; and

FIGS. 82A and 82B are rear views of alternative expandable fusiondevices having different attachable plates in accordance withembodiments of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The following description of the preferred embodiment(s) is merelyexemplary in nature and is in no way intended to limit the invention,its application, or uses.

A spinal fusion is typically employed to eliminate pain caused by themotion of degenerated disk material. Upon successful fusion, a fusiondevice becomes permanently fixed within the intervertebral disc space.Looking at FIG. 1, an exemplary embodiment of an expandable fusiondevice 10 is shown between adjacent vertebral bodies 2 and 3. The fusiondevice 10 engages the endplates 4 and 5 of the adjacent vertebral bodies2 and 3 and, in the installed position, maintains normal intervertebraldisc spacing and restores spinal stability, thereby facilitating anintervertebral fusion. The expandable fusion device 10 can bemanufactured from a number of materials including titanium, stainlesssteel, titanium alloys, non-titanium metallic alloys, polymericmaterials, plastics, plastic composites, PEEK, ceramic, and elasticmaterials.

In an embodiment, the expandable fusion device 10 can be configured andsized to be placed down an endoscopic tube and into the disc spacebetween the adjacent vertebral bodies 2 and 3. For example, theexpandable fusion device 10 can be figured for insertion through anendoscopic tube, such as a cannula having a diameter equal to or lessthan about 15 millimeters (“mm”) and, alternatively, less than about 10mm. In one particular embodiment, the expandable fusion 10 may beconfigured for insertion through a cannula having a diameter of about8.5 mm. In some embodiments, the expandable fusion device 10 may have awidth in a range of from about 8 mm to about 12 mm and a length in arange of from about 22 mm to about 34 mm. In some embodiments, theexpandable fusion device 10 may have an initial height in an unexpandedposition of less than about 15 mm and, alternatively, less than about 10mm. In one particular embodiment, the expandable fusion device 10 mayhave an initial height in an unexpanded position of about 8.5 mm. Insome embodiments, the expandable fusion device 10 may be expanded to aheight that is equal to or greater than about 150% of its initialheight. In one embodiment, the expandable fusion device 10 may beexpanded to a height that is equal to or greater than about 170% of itsinitial height. For example, the expandable fusion device 10 may beexpanded from an initial height of about 8 mm to a height in theexpanded position of about 14 mm.

In an exemplary embodiment, bone graft or similar bone growth inducingmaterial can be introduced around and within the fusion device 10 tofurther promote and facilitate the intervertebral fusion. The fusiondevice 10, in one embodiment, is preferably packed with bone graft orsimilar bone growth inducing material to promote the growth of bonethrough and around the fusion device. Such bone graft may be packedbetween the endplates of the adjacent vertebral bodies prior to,subsequent to, or during implantation of the fusion device.

With reference to FIGS. 2-7, an embodiment of the fusion device 10 isshown. In an exemplary embodiment, the fusion device 10 includes a firstendplate 14, a second endplate 16, a central ramp 18, and a driving ramp260. In an embodiment, the expandable fusion device 10 can be configuredto be placed down an endoscopic tube and into the disc space between theadjacent vertebral bodies 2 and 3. One or more components of the fusiondevice 10 may contain features, such as through bores that facilitateplacement down an endoscopic tube. In an embodiment, components of thefusion device 10 are placed down the endoscopic tube with assembly ofthe fusion device 10 in the disc space.

Although the following discussion relates to the second endplate 16, itshould be understood that it also equally applies to the first endplate14 as the second endplate 16 is substantially identical to the firstendplate 14 in embodiments of the present invention. Turning now toFIGS. 2-7 and 10, in an exemplary embodiment, the second endplate 16 hasa first end 39 and a second end 41. In the illustrated embodiment, thesecond endplate 16 further comprise an upper surface 40 connecting thefirst end 39 and the second end 41, and a lower surface 42 connectingthe first end 39 and the second end 41. In an embodiment, the secondendplate 16 further comprises a through opening 44, as seen on FIG. 11.The through opening 44, in an exemplary embodiment, is sized to receivebone graft or similar bone growth inducing material and further allowthe bone graft or similar bone growth inducing material to be packed inthe central opening in the central ramp 18.

As best seen in FIGS. 7 and 10, the lower surface 42 includes at leastone extension 46 extending along at least a portion of the lower surface42, in an embodiment. In an exemplary embodiment, the extension 46 canextend along a substantial portion of the lower surface 42, including,along the center of the lower surface 42. In the illustrated embodiment,the extension 46 includes a generally concave surface 47. The concavesurface 47 can form a through bore with the corresponding concavesurface 47 (not illustrated) of the first endplate 14, for example, whenthe device 10 is in an unexpanded configuration. In another exemplaryembodiment, the extension 46 includes at least one ramped surface 48. Inanother exemplary embodiment, there are two ramped surfaces 48, 50 withthe first ramped surface 48 facing the first end 39 and the secondramped surface facing the second end 41. In an embodiment, the firstramped surface 48 can be proximate the first end 39, and the secondramped surface 50 can be proximate the second end 41. It is contemplatedthat the slope of the ramped surfaces 48, 50 can be equal or can differfrom each other. The effect of varying the slopes of the ramped surfaces48, 50 is discussed below.

In one embodiment, the extension 46 can include features for securingthe endplate 16 when the expandable fusion device 10 is in an expandedposition. In an embodiment, the extension 46 includes one or moreprotuberances 49 extending from the lateral sides 51 of the extension.In the illustrated embodiment, there are two protuberances 49 extendingfrom each of the lateral sides 51 with each of the sides 53 having oneof the protuberances 49 extending from a lower portion of either end. Aswill be discussed in more detail below, the protuberances 49 can befigured to engage the central ramp 18 preventing and/or restrictinglongitudinal movement of the endplate 16 when the device 10 is in anexpanded position.

As illustrated in FIGS. 2-5, in one embodiment, the upper surface 40 ofthe second endplate 16 is flat and generally planar to allow the uppersurface 40 of the endplate 16 to engage with the adjacent vertebral body2. Alternatively, as shown in FIG. 15, the upper surface 40 can becurved convexly or concavely to allow for a greater or lesser degree ofengagement with the adjacent vertebral body 2. It is also contemplatedthat the upper surface 40 can be generally planar but includes agenerally straight ramped surface or a curved ramped surface. The rampedsurface allows for engagement with the adjacent vertebral body 2 in alordotic fashion. While not illustrated, in an exemplary embodiment, theupper surface 40 includes texturing to aid in gripping the adjacentvertebral bodies. Although not limited to the following, the texturingcan include teeth, ridges, friction increasing elements, keels, orgripping or purchasing projections.

Referring now to FIGS. 2-8, in an exemplary embodiment, the central ramp18 has a first end 20, a second end 22, a first side portion 24connecting the first end 20 and the second end 22, and a second sideportion 26 (best seen on FIG. 5) on the opposing side of the centralramp 12 connecting the first end 20 and the second end 22. The firstside portion 24 and the second side portion 26 may be curved, in anexemplary embodiment. The central ramp 18 further includes a lower end28, which is sized to receive at least a portion of the first endplate14, and an upper end 30, which is sized to receive at least a portion ofthe second endplate 16.

The first end 20 of the central ramp 18, in an exemplary embodiment,includes an opening 32. The opening 32 can be configured to receive anendoscopic tube in accordance with one or more embodiments. The firstend 20 of the central ramp 18, in an exemplary embodiment, includes atleast one angled surface 33, but can include multiple angled surfaces.The angled surface 33 can serve to distract the adjacent vertebralbodies when the fusion device 10 is inserted into an intervertebralspace.

The second end 22 of the central ramp 18, in an exemplary embodiment,includes an opening 36. The opening 36 extends from the second end 22 ofthe central ramp 18 into a central guide 37 in the central ramp 18.

In an embodiment, the central ramp 18 further includes one or moreramped surfaces 33. As best seen in FIG. 8, the one or more rampedsurfaces 33 positioned between the first side portion 24 and the secondside portion 26 and between the central guide 37 and the second end 22.In an embodiment, the one or more ramped surfaces 33 face the second end22 of the central ramp 18. In one embodiment, the central ramp 18includes two ramped surfaces 33 with one of the ramped surfaces 33 beingsloped upwardly and the other of the ramped surfaces 33 being slopeddownwardly. The ramped surfaces 33 of the central ramp can be configuredand dimensioned to engage the ramped surface 48 in each of the first andsecond endplates 14, 16.

Although the following discussion relates to the second side portion 26of the central ramp 18, it should be understood that it also equallyapplies to the first side portion 24 in embodiments of the presentinvention. In the illustrated embodiment, the second side portion 26includes an inner surface 27. In an embodiment, the second side portion26 further includes a lower guide 35, a central guide 37, and an upperguide 38. In the illustrated embodiment, the lower guide 35, centralguide 37, and the upper guide 38 extend out from the inner surface 27from the second end 22 to the one or more ramped surfaces 31. In theillustrated embodiment, the second end 22 of the central ramp 18 furtherincludes one or more guides 38. The guides 38 can serve to guide thetranslational movement of the first and second endplates 14, 16 withrespect to the central ramp 18. For example, protuberances 49 on thesecond endplate 16 may be sized to be received between the central guide37 and the upper guide 38. Protuberances 49 of the first endplate 16 maybe sized to be received between the central guide 37 and the lower guide35. A first slot 29 may be formed proximate the middle of the upperguide 38. A second slot 31 may be formed between end of the upper guide38 and the one or more ramped surfaces 33. The protuberances 49 may besized to be received within the first slot 29 and/or the second slot 31when the device 10 is in the expanded position.

Referring now to FIGS. 4-7 and 9, the driving ramp 260 has a throughbore 262. In an embodiment, the driving ramp 260 is generallywedge-shaped. As illustrated, the driving ramp 260 may comprise a wideend 56, a narrow end 58, a first side portion 60 connecting the wide end56 and the narrow end 58, and a second side portion 62 connecting thewide end 56 and the narrow end 58. The driving ramp 260 further maycomprise ramped surfaces, including an upper ramped surface 64 and anopposing lower ramped surface 66. The upper ramped surface 64 and thelower ramped surface 66 may be configured and dimensioned to engage theramped surface 50 proximate the second end 41 in of the first and thesecond endplates 14, 16. The first and second side portions 60, 62 mayeach include grooves 68 that extend, for example, in a directionparallel to the longitudinal axis of the through bore 262. The grooves68 may be sized to receive the central guide 37 on the interior surface27 of each of the side portions 24, 26 of the central ramp 18. In thismanner, the grooves 68 together with the central guide 37 can surface toguide the translational movement of the driving ramp 260 in the centralramp 18.

A method of installing the expandable fusion device 10 of FIG. 1 is nowdiscussed in accordance with one embodiment of the present invention.Prior to insertion of the fusion device 10, the intervertebral space isprepared. In one method of installation, a discectomy is performed wherethe intervertebral disc, in its entirety, is removed. Alternatively,only a portion of the intervertebral disc can be removed. The endplatesof the adjacent vertebral bodies 2, 3 are then scraped to create anexposed end surface for facilitating bone growth across theintervertebral space. One or more endoscopic tubes can then be insertedinto the disc space. The expandable fusion device 10 can then beintroduced into the intervertebral space down an endoscopic tube andseated in an appropriate position in the intervertebral disc space.

After the fusion device 10 has been inserted into the appropriateposition in the intervertebral disc space, the fusion device 10 can thenbe expanded into the expanded position. To expand the fusion device 10,the driving ramp 260 may moved in a first direction with respect to thecentral ramp 18. Translational movement of the driving ramp 260 throughthe central ramp 18 may be guided by the central guide 37 on each of thefirst and second side portions 24, 26 of the central ramp 18. As thedriving ramp 260 moves, the upper ramped surface 64 pushes against theramped surface 50 proximate the second end 41 of the second endplate 16,and the lower ramped surface 66 pushes against the ramped surface 50proximate the second end 41 of the first endplate 14. In addition, theramped surfaces 33 in the central ramp 18 push against the rampedsurface 48 proximate the first end 41 of the first and second endplates14, 16. In this manner, the first and second endplates 14, 16 are pushedoutwardly into an expanded configuration. As discussed above, thecentral ramp 16 includes locking features for securing the endplates 14,16.

It should also be noted that the expansion of the endplates 14, 16 canbe varied based on the differences in the dimensions of the rampedsurfaces 48, 50 and the angled surfaces 62, 64. As best seen in FIG. 16,the endplates 14, 16 can be expanded in any of the following ways:straight rise expansion, straight rise expansion followed by a toggleinto a lordotic expanded configuration, or a phase off straight riseinto a lordotic expanded configuration.

Turning back to FIGS. 2-7, in the event the fusion device 10 needs to berepositioned or revised after being installed and expanded, the fusiondevice 10 can be contracted back to the unexpanded configuration,repositioned, and expanded again once the desired positioning isachieved. To contract the fusion device 10, the central ramp 18 is movedwith respect to the central ramp 260 away from the central ramp 260. Asthe central ramp 18 moves, the ramped surfaces 33 in the central ramp 18ride along the ramped surfaces 48 of the first and second endplates 14,16 with the endplates 14, 16 moving inwardly into the unexpandedposition.

With reference now to FIG. 17, fusion device 10 is shown with anexemplary embodiment of artificial endplates 100. Artificial endplates100 allows the introduction of lordosis even when the endplates 14 and16 of the fusion device 10 are generally planar. In one embodiment, theartificial endplates 100 have an upper surface 102 and a lower surface104. The upper surfaces 102 of the artificial endplates 100 have atleast one spike 106 to engage the adjacent vertebral bodies. The lowersurfaces 104 have complementary texturing or engagement features ontheir surfaces to engage with the texturing or engagement features onthe upper endplate 14 and the lower endplate 16 of the fusion device 10.In an exemplary embodiment, the upper surface 102 of the artificialendplates 100 have a generally convex profile and the lower surfaces 104have a generally parallel profile to achieve lordosis. In anotherexemplary embodiment, fusion device 10 can be used with only oneartificial endplate 100 to introduce lordosis even when the endplates 14and 16 of the fusion device 10 are generally planar. The artificialendplate 100 can either engage endplate 14 or engage endplate 16 andfunction in the same manner as described above with respect to twoartificial endplates 100.

With reference to FIGS. 11-14, an embodiment for placing an expandablefusion device 10 into an intervertebral disc space is illustrated. Theexpandable fusion device 10 can be introduced into the intervertebralspace down an endoscopic tube utilizing a tool 70 that is attached toendplate 16, with the second endplate 16 being first placed down thetube with tool 70 and into the disc space, as seen in FIG. 11. Afterinsertion of the second endplate 16, the first endplate 14 can be placeddown the same endoscopic tube with tool 72 and into the disc space, asshown on FIG. 12. Following the first endplate 14, the central ramp 12can be placed down the same endoscopic tube and into the disc spaceguided by tools 70 and 72, as shown on FIGS. 13 and 14.

Referring now to FIGS. 18-23, an alternative embodiment of theexpandable fusion device 10 is shown. In an exemplary embodiment, thefusion device 10 includes a first endplate 14, a second endplate 16, acentral ramp 18, and an actuator assembly 200. As will be discussed inmore detail below, the actuator assembly 200 drives the central ramp 18which forces apart the first and second endplates 14, 16 to place theexpandable fusion device in an expanded position. One or more componentsof the fusion device 10 may contain features, such as through bores,that facilitate placement down an endoscopic tube. In an embodiment,components of the fusion device 10 are placed down the endoscopic tubewith assembly of the fusion device 10 in the disc space.

Although the following discussion relates to the second endplate 16, itshould be understood that it also equally applies to the first endplate14 as the second endplate 16 is substantially identical to the firstendplate 14 in embodiments of the present invention. With additionalreference to FIG. 24, in an exemplary embodiment, the second endplate 16has a first end 39 and a second end 41. In the illustrated embodiment,the second endplate 16 further comprise an upper surface 40 connectingthe first end 39 and the second end 41, and a lower surface 42connecting the first end 39 and the second end 41. While notillustrated, in an embodiment, the second endplate 16 further comprisesa through opening. The through opening, in an exemplary embodiment, issized to receive bone graft or similar bone growth inducing material.

In one embodiment, the upper surface 40 of the second endplate 16 isflat and generally planar to allow the upper surface 40 of the endplate16 to engage with the adjacent vertebral body 2. Alternatively, as shownin FIG. 15, the upper surface 40 can be curved convexly or concavely toallow for a greater or lesser degree of engagement with the adjacentvertebral body 2. It is also contemplated that the upper surface 40 canbe generally planar but includes a generally straight ramped surface ora curved ramped surface. The ramped surface allows for engagement withthe adjacent vertebral body 2 in a lordotic fashion. While notillustrated, in an exemplary embodiment, the upper surface 40 includestexturing to aid in gripping the adjacent vertebral bodies. Although notlimited to the following, the texturing can include teeth, ridges,friction increasing elements, keels, or gripping or purchasingprojections.

In one embodiment, the second endplate 16 further comprises a first sideportion 202 connecting the first end 39 and the second end 41, and asecond side portion 204 connecting the first end 39 and the second end41. In the illustrated embodiment, the first and second side portions202, 204 are extensions from the lower surface 42. In an exemplaryembodiment, the first and second side portions 202, 204 each includeramped surfaces 206, 208. In the illustrated embodiment, the rampedsurfaces 206, 208 extend from the first end 39 of the second endplate 16to bottom surfaces 210, 212 of each of the side portions 202, 204. Inone embodiment, the ramped surfaces 206, 208 are forward facing in thatthe ramped surfaces 206, 208 face the first end 39 of the secondendplate. As previously discussed, the slope of the ramped surfaces 206,208 may be varied as desired for a particular application.

In an embodiment, the first and second side portions 202, 204 eachcomprise at least one protuberance 214. In an exemplary embodiment, thefirst and second side portions 202, 204 each comprise a firstprotuberance 214, a second protuberance 216, and a third protuberance218. In one embodiment, the protuberances 214, 216, 218 extend from theinterior surface 220 of the first and second side portions 202, 204. Inan exemplary embodiment, the protuberances 214, 216, 218 extend at thelower side of the interior surface 220. As best seen in FIG. 24, thefirst and the second protuberances 214, 216 form a first slot 222, andthe second and third protuberances 216, 218 form a second slot 224.

As best seen in FIG. 24, the lower surface 42 of the second endplate 16,in an embodiment, includes a central extension 224 extending along atleast a portion of the lower surface. In the illustrated embodiment, thecentral extension 224 extends between the first and second side portions202 and 204. In an exemplary embodiment, the central extension 224 canextend from the second end 41 of the endplate 16 to the central portionof the endplate. In one embodiment, the central extension 224 includes agenerally concave surface 226 configured and dimensioned to form athrough bore with the corresponding concave surface 226 (notillustrated) of the first endplate 14. The central extension 224 canfurther include, in an exemplary embodiment, a ramped surface 228. Inthe illustrated embodiment, the ramped surface 228 faces the first end39 of the endplate 16. The ramped surface 228 can be at one end of thecentral extension 224. In an embodiment, the other end of the centralextension 224 forms a stop 230. In the illustrated embodiment, the stop230 is recessed from the second end 41 of the second endplate 16.

Referring to FIGS. 25-27, in an exemplary embodiment, the central ramp18 includes a body portion 232 having a first end 234 and a second end236. In an embodiment, the body portion 232 includes at least a firstexpansion portion 238. In an exemplary embodiment, the body portion 232includes a first expansion portion 238 and a second expansion portion240 extending from opposing sides of the body portion with each of thefirst and second expansion portions 238, 240 having a generallytriangular cross-section. In one embodiment, the expansion portions 238,240 each have angled surfaces 242, 244 configured and dimensioned toengage the ramped surfaces 206, 208 of the first and second endplates14, 16 and force apart the first and second endplates 14, 16. In anembodiment, the engagement between the angled surfaces 242, 244 of theexpansion portions 238, 240 with the ramped surfaces 206, 208 of thefirst and second endplates 14, 16 may be described as a dovetailconnection.

The second end 236 of the central ramp 18, in an exemplary embodiment,includes opposing angled surfaces 246. The angled surfaces 246 can beconfigured and dimensioned to engage the ramped surface 228 in thecentral extension 224 in each of the first and second endplates 14, 16.In other words, one of the angled surfaces 246 can be upwardly facingand configured, in one embodiment, to engage the ramped surface 228 inthe central extension 224 in the second endplate 16. In an embodiment,the engagement between the angled surfaces 246 of the second end 236 ofthe central ramp 18 with the ramped surface 228 in the first and secondendplates 14, 16 may be described as a dovetail connection.

The second end 236, in an exemplary embodiment, can further include anextension 252. In the illustrated embodiment, the extension 252 isgenerally cylindrical in shape with a through bore 254 extendinglongitudinally therethrough. In one embodiment, the extension 252 caninclude a beveled end 256. While not illustrated, at least a portion ofthe extension 252 can be threaded.

Referring still to FIGS. 25-27, the central ramp 18 can further includefeatures for securing the first and second endplates 14, 16 when theexpandable fusion device 10 is in an expanded position. In anembodiment, the body portion 232 of the central ramp 18 includes one ormore protuberances 248, 250 extending from opposing sides of the bodyportion 232. As illustrated, the protuberances 248, 250, in oneembodiment, can be spaced along the body portion 232. In an exemplaryembodiment, the protuberances 248, 250 can be configured and dimensionedfor insertion into the corresponding slots 222, 224 in the first andsecond endplates 14, 16 when the device 10 is in an expanded position,as best seen in FIGS. 19 and 21. The protuberances 248, 250 can engagethe endplates 14, 16 preventing and/or restricting movement of theendplates 14, 16 with respect to the central ramp 18 after expansion ofthe device 10.

With reference to FIGS. 20-23, in an exemplary embodiment, the actuatorassembly 200 has a flanged end 253 configured and dimensioned to engagethe stop 232 in the central extension 224 of the first and the secondendplates 14, 16. In an embodiment, the actuator assembly 200 furtherincludes an extension 254 that extends from the flanged end 253. In afurther embodiment, the actuator assembly 200 includes a threaded hole256 that extends through the actuator assembly 200. It should beunderstood that, while the threaded hole 256 in the actuator assembly200 is referred to as threaded, the threaded hole 256 may only bepartially threaded in accordance with one embodiment. In an exemplaryembodiment, the threaded hole 256 is configured and dimensioned tothreadingly receive the extension 252 of the central ramp 18.

With additional reference to FIGS. 28-32, a method of installing theexpandable fusion device 10 of FIGS. 18-27 is now discussed inaccordance with one embodiment of the present invention. Prior toinsertion of the fusion device, the disc space may be prepared asdescribed above and then one or more endoscopic tubes may then insertedinto the disc space. The expandable fusion device 10 can then beinserted into and seated in the appropriate position in theintervertebral disc space, as best seen in FIGS. 28-32. The expandablefusion device 10 can be introduced into the intervertebral space down anendoscopic tube (not illustrated), with the central ramp 18 being firstplaced down the tube and into the disc space, as seen in FIG. 28. Afterinsertion of the central ramp, the first endplate 14 can be placed downan endoscopic tube, as shown on FIG. 29, followed by insertion of thesecond endplate 16, as shown on FIG. 30. After the second endplate 16,the actuator assembly 200 can then be inserted to complete assembly ofthe device 10, as best seen in FIG. 31.

After the fusion device 10 has been inserted into and assembled in theappropriate position in the intervertebral disc space, the fusion device10 can then be expanded into the expanded position. To expand the fusiondevice 10, the actuator assembly 200 can be rotated. As discussed above,the actuator assembly 200 is in threaded engagement with the extension250 of the central ramp 18. Thus, as the actuator assembly 200 isrotated in a first direction, the central ramp 18 moves toward theflanged end 253 of the actuator assembly 200. In another exemplaryembodiment, the actuator assembly 200 can be moved in a linear directionwith the ratchet teeth as means for controlling the movement of thecentral ramp 18. As the central ramp 18 moves, the angled surfaces 242,244 in the expansion portions 238, 240 of the central ramp 18 pushagainst the ramped surfaces 206, 208 in the first and second sideportions 202, 204 of the first and second endplates 14, 16. In addition,the angled surfaces 246 in the second end 236 of the central ramp 18also push against the ramped surfaces 228 in the central extension 224of each of the endplates 14, 16. This is best seen in FIGS. 22-23.

Since the expansion of the fusion device 10 is actuated by a rotationalinput, the expansion of the fusion device 10 is infinite. In otherwords, the endplates 14, 16 can be expanded to an infinite number ofheights dependent on the rotational advancement of the actuator assembly200. As discussed above, the central ramp 16 includes locking featuresfor securing the endplates 14, 16.

In the event the fusion device 10 needs to be repositioned or revisedafter being installed and expanded, the fusion device 10 can becontracted back to the unexpanded configuration, repositioned, andexpanded again once the desired positioning is achieved. To contract thefusion device 10, the actuator assembly 200 can be rotated in a seconddirection. As discussed above, actuator assembly 200 is in threadedengagement with the extension 250 of the central ramp 18; thus, as theactuator assembly 200 is rotated in a second direction, opposite thefirst direction, the central ramp 18 moves with respect to the actuatorassembly 200 and the first and second endplates 14, 16 away from theflanged end 253. As the central ramp 18 moves, the first and secondendplates are pulled inwardly into the unexpanded position.

Referring now to FIGS. 33-38, an alternative embodiment of theexpandable fusion device 10 is shown. In the illustrated embodiment, thefusion device includes a first endplate 14, a second endplate 16, acentral ramp 18, and an actuator assembly 200. The fusion device 10 ofFIGS. 33-38 and its individual components are similar to the device 10illustrated on FIGS. 18-23 with several modifications. The modificationsto the device 10 will be described in turn below.

Although the following discussion relates to the second endplate 16, itshould be understood that it also equally applies to the first endplate14 as the second endplate 16 is substantially identical to the firstendplate 14 in embodiments of the present invention. With additionalreference to FIG. 39, in an exemplary embodiment, the lower surface 42of the second endplate 16 has been modified. In one embodiment, thecentral extension 224 extending from the lower surface 42 has beenmodified to include a second ramped surface 258 rather than a stop. Inan exemplary embodiment, the second ramped surface 258 faces the secondend 41 of the second endplate 16. In contrast, ramped surface 228 on thecentral extension 228 faces the first end 39 of the second endplate. Theconcave surface 228 connects the ramped surface 228 and the secondramped surface 258.

With reference to FIGS. 35-38, in an exemplary embodiment, the actuatorassembly 200 has been modified to further include a driving ramp 260. Inthe illustrated embodiment, the driving ramp 260 has a through bore 262through which the extension 254 extends. In an embodiment, the drivingramp 260 is generally wedge-shaped. As illustrated, the driving ramp 260may comprise a blunt end 264 in engagement with the flanged end 253. Inan exemplary embodiment, the driving ramp 260 further comprises angledsurfaces 266 configured and dimensioned to engage the second rampedsurface 258 of each of the endplates 14, 16 and force apart the firstand second endplates 14, 16.

Referring now to FIGS. 40-44, an alternative embodiment of theexpandable fusion device 10 is shown. In the illustrated embodiment, thefusion device 10 includes a first endplate 14, a second endplate 16, acentral ramp 18, an actuator assembly 200, and a driving ramp 300. Aswill be discussed in more detail below, the actuator assembly 200functions, in an embodiment, to pull the central ramp 18 and the drivingramp 300 together, which forces apart the first and second endplates 14,16. In an embodiment, the expandable fusion device.

Although the following discussion relates to the first endplate 14, itshould be understood that it also equally applies to the second endplate16 as the second endplate 16 is substantially identical to the firstendplate 14 in embodiments of the present invention. With reference toFIGS. 40-45, in an exemplary embodiment, the first endplate 14 has afirst end 39 and a second end 41. In the illustrated embodiment, thefirst endplate 14 further comprises an upper surface 40 connecting thefirst end 39 and the second end 41, and a lower surface 42 connectingthe first end 39 and the second end 41. While not illustrated, in anembodiment, the first endplate 14 may comprise further comprises athrough opening. The through opening, in an exemplary embodiment, issized to receive bone graft or similar bone growth inducing material.

In one embodiment, the upper surface 40 of the first endplate 14 is flatand generally planar to allow the upper surface 40 of the endplate 14 toengage with the adjacent vertebral body 2. Alternatively, as shown inFIG. 15, the upper surface 40 can be curved convexly or concavely toallow for a greater or lesser degree of engagement with the adjacentvertebral body 2. It is also contemplated that the upper surface 40 canbe generally planar but includes a generally straight ramped surface ora curved ramped surface. The ramped surface allows for engagement withthe adjacent vertebral body 2 in a lordotic fashion. While notillustrated, in an exemplary embodiment, the upper surface 40 includestexturing to aid in gripping the adjacent vertebral bodies. Although notlimited to the following, the texturing can include teeth, ridges,friction increasing elements, keels, or gripping or purchasingprojections.

In one embodiment, the first endplate 14 further comprises a first sideportion 202 connecting the first end 39 and the second end 41, and asecond side portion 204 connecting the first end 39 and the second end41. In the illustrated embodiment, the first and second side portions202, 204 are extensions from the lower surface 42. In an embodiment, thefirst and second side portions each have an interior surface 302 and anexterior surface 304. In an exemplary embodiment, the first and secondside portions 202, 204 each include one or more ramped portions. In theillustrated embodiment, the first and second side portions 202, 204include first ramped portions 306, 308 at the first end 39 of theendplate 14 and second ramped portions 310, 312 at the second end 41 ofthe endplate. The first and second side portions 202, 204 each caninclude a bridge portion 314 connecting the first ramped portions 306,308 and the second ramped portions 310, 312. In an embodiment, the firstramped portions 306, 308 abut the exterior surface 304 of the respectiveside portions 202, 204, and the second ramped portions 310, 312 abut theinterior surface 302 of the respective side portions 202, 204. Asillustrated, the first ramped portions 306, 308 may include tongueportions 316, 318 with the tongue portions 316, 318 extending in anoblique direction with respect to the upper surface 40 of the endplate14. As further illustrated, the second ramped portions 310, 312 mayinclude tongue portions 320, 322 that extend in an oblique directionwith respect to the upper surface 40 of the endplate 14.

As best seen in FIG. 45, the lower surface 42 of the second endplate 16,in an embodiment, includes a central extension 224 extending along atleast a portion of the lower surface. In the illustrated embodiment, thecentral extension 224 extends between the first and second side portions202 and 204. In an exemplary embodiment, the central extension 224 canextend generally between the first ramped portions 306, 308 and thesecond ramped portions 310, 312. In one embodiment, the centralextension 224 includes a generally concave surface 226 configured anddimensioned to form a through bore with the corresponding concavesurface 226 (not illustrated) of the second endplate 16.

With reference to FIGS. 43 and 44, the actuator assembly 200 includes ahead portion 324, a rod receiving extension 326, and a connectingportion 328 that connecting portions that connects the head portion 324and the rod receiving extension 326. As illustrated, the head portion324 may include one or more instrument gripping features 330 that canallow it to be turned by a suitable instrument. In addition, the headportion 324 has a larger diameter than the other components of theactuator assembly 200 to provide a contact surface with the driving ramp300. In the illustrated embodiment, the head portion 324 includes a rim332 that provides a surface for contacting the driving ramp 300. As canbe seen in FIG. 44, in an exemplary embodiment, the rod receivingextension 326 includes an opening sized and dimensioned to receive theextension 336 of the central ramp 18. In an embodiment, the rodreceiving extension 326 includes threading for threadingly engaging theextension 336. In another embodiment, the rod receiving extension 326includes ratchet teeth for engaging the extension 336. In theillustrated embodiment, the head portion 324 and the rod receivingextension 326 are connected by connecting portion 328 which can begenerally cylindrical in shape.

With reference to FIGS. 43, 44, and 46, the central ramp 18 includesexpansion portion 334 and extension 336. As best seen in FIG. 46, theexpansion portion 334 may include an upper portion 338 and side portions340, 342 that extend down from the upper portion 338. In an embodiment,each of the side portions 340, 342 include dual, overlapping rampedportions. For example, side portions 340, 342 each include a firstramped portion 344 that overlaps a second ramped portion 346. In theillustrated embodiment, the first ramped portion 344 faces the extension336 while the second ramped portion 344 faces away from the extension336. In one embodiment, angled grooves 348, 350 are formed in each ofthe first and second ramped portions 344, 346. In another embodiment,the angled grooves 348, 350 are sized to receive the correspondingtongues 316, 318, 320, 322 in the first and second endplates with angledgrooves 348 receiving tongues 320, 322 in the second endplate 16 andangled grooves 350 receiving tongues 316, 318 in the first endplate 14.Although the device 10 is described with tongues 316, 318, 320, 322 onthe endplates 14, 16 and angled grooves 348, 350 on the central ramp 18,it should be understood that that device 10 can also be configured withgrooves on the endplates 14, 16 and tongues on the central ramp 18, inaccordance with one embodiment of the present invention.

In an exemplary embodiment, the extension 336 is sized to be receivedwithin the rod receiving extension 326 of the actuator assembly 200. Inone embodiment, the extension 336 has threading with the extension 336being threadingly received within the rod receiving extension 326. Inanother embodiment, the extension 336 has ratchet teeth with theextension 336 being ratcheted into the rod receiving extension 336. Inan embodiment, the extension 336 include nose 352 at the end of theextension 336.

With reference to FIGS. 47-49, in an exemplary embodiment, the drivingramp 300 includes an upper portion 354 having an upper surface 356 andan oblique surface 358. In an embodiment, the driving ramp 300 furtherincludes side portions 360, 362 that extend from the upper portion 354connecting the upper portion 354 with the lower portion 364 of thedriving ramp 300. As best seen in FIGS. 48-49, the driving ramp 300further includes a bore 366, in an exemplary embodiment, sized toreceive the connection portion 328 of the actuator assembly 200. In oneembodiment, the driving ramp 300 moves along the connection portion 328when the actuator assembly 200 is pushing the driving ramp 300. In anexemplary embodiment, the driving ramp 300 further includes contactsurface 368 that engages the rim 332 of the head portion 324 of theactuator assembly 200. In the illustrated embodiment, the contactsurface 368 has a generally annular shape.

In an exemplary embodiment, the side portions 360, 362 of the drivingramp 300 each include overlapping ramped portions. For example, the sideportions 360, 362 each include first ramped portions 370 that overlapsecond ramped portions 372. In the illustrated embodiment, the firstramped portions 370 face central ramp 18 while the second rampedportions 372 face the opposite direction. In one embodiment, angledgrooves 374, 376 are formed in each of the first and second rampedportions 370, 372. FIG. 48 is a perspective view of the driving ramp 300that shows the top ends of the angled grooves 374 in ramped portions370. FIG. 49 is a perspective view of the driving ramp 300 that showsthe top ends of the angled grooves 376 in ramped portions 372. In anexemplary embodiment, the angled grooves 374, 376 are sized to receivecorresponding tongues 316, 318, 320, 322 in the first and secondendplates 14, 16 with angled grooves 370 receiving tongues 316, 318 inthe second endplate 16 and angled grooves 372 receiving tongues 320, 322in the first endplate 14. Although the device 10 is described withtongues 316, 318, 320, 322 in the first and second endplates 14, 16 andangled grooves 370, 372, 374, 376 on the driving ramp 300, it should beunderstood that that device 10 can also be configured with grooves onthe second endplate 16 and tongues on the driving ramp 300, inaccordance with one embodiment of the present invention.

Turning now to FIGS. 40-42, a method of installing the expandable fusiondevice 10 of FIGS. 40-49 is now discussed in accordance with oneembodiment of the present invention. Prior to insertion of the fusiondevice, the disc space may be prepared as described above. Theexpandable fusion device 10 can then be inserted into and seated in theappropriate position in the intervertebral disc space. The expandablefusion device 10 is then introduced into the intervertebral space, withthe end having the expansion portion 334 of the central ramp 18 beinginserted. In an exemplary method, the fusion device 10 is in theunexpanded position when introduced into the intervertebral space. In anexemplary method, the intervertebral space may be distracted prior toinsertion of the fusion device 10. The distraction provide some benefitsby providing greater access to the surgical site making removal of theintervertebral disc easier and making scraping of the endplates of thevertebral bodies 2, 3 easier.

With the fusion device 10 inserted into and seated in the appropriateposition in the intervertebral disc space, the fusion device can thenexpanded into the expanded position, as best seen in FIG. 42. To expandthe fusion device 10, an instrument is engaged with the head portion 324of the actuator assembly 200. The instrument is used to rotate actuatorassembly 200. As discussed above, actuator assembly 200 is threadinglyengaged with the extension 336 of the central ramp 18; thus, as theactuator assembly 200 is rotated in a first direction, the central ramp18 is pulled toward the actuator assembly 200. In an exemplaryembodiment, the actuator assembly 200 is moved in a linear directionwith the ratchet teeth engaging as means for controlling the movement ofthe actuator assembly 200 and the central ramp 18. As the central ramp18 is pulled towards the actuator assembly 200, the first rampedportions 344 of the central ramp 18 push against the second rampedportions 310, 312 of the second endplate 16 and the second rampedportions 346 of the central ramp 18 push against first ramped portions306, 308 of the first endplate 14. In this manner, the central ramp 18acts to push the endplates 14, 16 outwardly into the expanded position.This can best be seen in FIGS. 40-42. As the endplates 14, 16 moveoutwardly the tongues 316, 318, 320, 322 in the endplates 14, 16 ride inthe angled grooves 348, 350 with the tongues 320, 322 in the secondendplate 16 riding in angled grooves 348 and the tongues 316, 318 in thefirst endplate 14 riding in angled grooves 350.

As discussed above, the actuator assembly 200 also engages driving ramp300; thus, as the actuator assembly 200 is rotated in a first direction,the actuator assembly 200 pushes the driving ramp 300 towards thecentral ramp 18 in a linear direction. As the driving ramp 300 is pushedtowards the central ramp 18, the first ramped portions 370 of thedriving ramp 300 push against the first ramped portions 306, 308 of thesecond endplate 16 and the second ramped portions 372 of the drivingramp 300 push against the second ramped portions 310, 312 of the firstendplate 14. In this manner, the driving ramp 300 also acts to push theendplates 14, 16 outwardly into the expanded position. This can best beseen in FIGS. 40-42. As the endplates 14, 16 move outwardly the tongues316, 318, 320, 322 in the endplates 14, 16 ride in the angled grooves370, 372 with the tongues 316, 318 in the second endplate 16 riding inangled grooves 370 and the tongues 320, 322 in the first endplate 14riding in angled grooves 372.

Since the expansion of the fusion device 10 is actuated by a rotationalinput, the expansion of the fusion device 10 is infinite. In otherwords, the endplates 14, 16 can be expanded to an infinite number ofheights dependent on the rotational advancement of the actuator assembly200.

Referring now to FIGS. 50-54, an alternative embodiment of theexpandable fusion device 10 is shown. In the illustrated embodiment, thefusion device 10 includes a first endplate 14, a second endplate 16, acentral ramp 18, an actuator assembly 200, and a driving ramp 300. Aswill be discussed in more detail below, the actuator assembly 200functions, in an embodiment, to pull the central ramp 18 and the drivingramp 300 together, which forces apart the first and second endplates 14,16. In an embodiment, the expandable fusion device may contain features,such as a through bore, that facilitate placement down an endoscopictube. In an embodiment, the assembled fusion device 10 may be placeddown the endoscopic tube and then expanded.

Although the following discussion relates to the first endplate 14, itshould be understood that it also equally applies to the second endplate16 as the second endplate 16 is substantially identical to the firstendplate 14 in embodiments of the present invention. It should beunderstood that, in an embodiment, the first endplate 14 is configuredto interlock with the second endplate 16. With additional reference toFIG. 55, in an exemplary embodiment, the first endplate 14 has a firstend 39 and a second end 41. As illustrated, the first end 39 may bewider than the second end 41. In the illustrated embodiment, the firstendplate 14 further comprises an upper surface 40 connecting the firstend 39 and the second end 41, and a lower surface 42 connecting thefirst end 39 and the second end 41. As best seen in FIG. 54, the lowersurface 42 can be curved concavely such that the first and secondendplates 14, 16 form a through bore when the device 10 is in a closedposition. In an embodiment, the first endplate 14 may comprise a throughopening 44. The through opening 44, in an exemplary embodiment, is sizedto receive bone graft or similar bone growth inducing material.

In one embodiment, the upper surface 40 of the first endplate 14 is flatand generally planar to allow the upper surface 40 of the endplate 14 toengage with the adjacent vertebral body 2. Alternatively, as shown inFIG. 15, the upper surface 40 can be curved convexly or concavely toallow for a greater or lesser degree of engagement with the adjacentvertebral body 2. It is also contemplated that the upper surface 40 canbe generally planar but includes a generally straight ramped surface ora curved ramped surface. The ramped surface allows for engagement withthe adjacent vertebral body 2 in a lordotic fashion. As illustrated, inan exemplary embodiment, the upper surface 40 includes texturing to aidin gripping the adjacent vertebral bodies. For example, the uppersurface 40 may further comprise texturing 400 to engage the adjacentvertebral bodies. Although not limited to the following, the texturingcan include teeth, ridges, friction increasing elements, keels, orgripping or purchasing projections.

In one embodiment, the first endplate 14 further comprises a first sideportion 202 connecting the first end 39 and the second end 41, and asecond side portion 204 connecting the first end 39 and the second end41. In the illustrated embodiment, the first and second side portions202, 204 are extensions from the lower surface 42. In an embodiment, thefirst and second side portions 202, 204 each include an interior surface302 and an exterior surface 304. In an embodiment, the first end 39 ofthe first endplate 14 is generally designed and configured to fit overthe second end 41 of the second endplate 16 when the device 10 is in aclosed position. As illustrated, the first and second side portions 202,204 each may include first ramped portions 306, 308, second rampedportions 310, 312, and/or central ramped portion 402.

In an embodiment, the first ramped portions 306, 308 are proximate thefirst end 39 of the endplate 14. In accordance with embodiment of thepresent invention, the first ramped portions 306, 308 of the firstendplate 14 are generally designed and configured to fit over the secondramped portions 310, 312 of the second endplate 16 when the device 10 isin a closed position. In an exemplary embodiment, the first rampedportions 306, 308 generally face the first end 39 and can extend in anoblique direction with respect to the upper surface 40, for example. Asillustrated, the first ramped portions 306, 308 may include tongueportions 316, 318 extending in an oblique direction with respect to theupper surface 40 of the endplate 14.

In an embodiment, the second ramped portions 310, 312 are proximate thesecond end 41 of the endplate 14. In an exemplary embodiment, the secondramped portions 310, 312 can extend in an oblique direction with respectto the upper surface 40 and generally face the second end 41. The firstand second side portions 202, 204, in an embodiment, each can include abridge portion 314 connecting the first ramped portions 306, 308 and thesecond ramped portions 310, 312. As further illustrated, the secondramped portions 310, 312 may include tongue portions 320, 322 thatextend in an oblique direction with respect to the upper surface 40 ofthe endplate 14.

In an embodiment, the endplate 14 further may include a central rampedportion 402 proximate the bridge portion 314. In the illustratedembodiment, the endplate 14 includes a central ramped portion 402proximate the bridge portion 314 of the second side portion 204. In anexemplary embodiment, the central ramped portion 402 can extend in anoblique direction with respect to the upper surface 40 and face thefirst end 39 of the endplate 14. As illustrated, the first rampedportions 306, 308 may include tongue portions 316, 318 with the tongueportions 316, 318 extending in an oblique direction with respect to theupper surface 40 of the endplate 14.

With reference to FIGS. 50-52 and 54, in an embodiment, the actuatorassembly 200 includes a head portion 324, an extension 404, and athrough bore 406 that extends longitudinally through the actuatorassembly 200. As illustrated, the head portion 324 may include one ormore instrument gripping features 330 that can allow it to be turned bya suitable instrument. In addition, the head portion 324 has a largerdiameter than the other components of the actuator assembly 200 toprovide a contact surface with the driving ramp 300. In the illustratedembodiment, the head portion 324 includes a rim 332 that provides asurface for contacting the driving ramp 300. In an embodiment, theextension 404 is a generally rod-like extension. In another embodiment,the extension 404 includes ratchet teeth for engaging the extension 336.

With reference to FIGS. 51, 52, and 56, the central ramp 18 has a firstend 408 and a second end 410. In an embodiment, the central ramp 18includes a first expansion portion 412, a second expansion portion 414,a rod-receiving extension 416, and a through bore 418 that extendslongitudinally through the central ramp 18. In an exemplary embodiment,first expansion portion 412 can be proximate the first end 408 of thecentral ramp 18. As best seen in FIG. 56, the first expansion portion412 may include side portions 420, 422. In an embodiment, each of theside portions 420, 422 includes dual, overlapping ramped portions thatextend in oblique directions with respect to the through bore 418. Forexample, side portions 420, 422 each include a first ramped portion 424that overlaps a second ramped portion 426. In the illustratedembodiment, the first ramped portion 424 faces the rod-receivingextension 416 while the second ramped portion 426 faces the oppositedirection. In one embodiment, angled grooves 428, 430 are formed in eachof the first and second ramped portions 424, 426. In an exemplaryembodiment, the angled grooves 428, 430 are sized to receive thecorresponding tongues 316, 318, 320, 322 in the first and secondendplates 14, 16 with angled grooves 428 receiving tongues 320, 322 inthe second endplate 16 and angled grooves 430 receiving tongues 316, 318in the first endplate 14. Although the device 10 is described withtongues 316, 318, 320, 322 on the endplates 14, 16 and angled grooves428, 430 on the central ramp 18, it should be understood that thatdevice 10 can also be configured with grooves on the endplates 14, 16and tongues on the central ramp 18, in accordance with one embodiment ofthe present invention.

In an embodiment, the second expansion portion 414 is located on therod-receiving extension 416 between the first end 408 and the second end410 of the central ramp 18. In an exemplary embodiment, the secondexpansion portion 414 includes central ramped portions 432. In oneembodiment, the second expansion portion 414 includes two central rampedportions 432 on opposite sides of the rod-receiving extension 416. In anexemplary embodiment, the central ramped portions 424 extend in anoblique direction with respect to the through bore 418 and face thesecond end 410 of the central ramp 18.

The rod-receiving extension 416 extends from the first expansion portion412 and has an opening 434 at the second end of the central ramp 18. Inan embodiment, the rod-receiving extension 416 is sized and configuredto receive the extension 404 of the actuator assembly 200. In anembodiment, the rod-receiving extension 416 has threading with therod-receiving extension 416 threadingly receiving extension 404 of theactuator assembly 200. In another embodiment, the rod-receivingextension 416 has ratchet teeth with the extension 404 being ratchetedinto the rod-receiving extension 416.

With reference to FIGS. 50-52 and 57, in an exemplary embodiment, thedriving ramp 300 includes an upper portion 354 having an upper surface356 and an oblique surface 358. In an embodiment, the driving ramp 300further includes a bore 366, in an exemplary embodiment, sized toreceive the extension 404 of the actuator assembly 200. In theillustrated, embodiment, the upper portion 354 has a hole 436 thatextends through the upper surface 356 to the bore 366. Set screw 438 maybe inserted through the hole 436 to secure the driving ramp 300 to theactuator assembly 200. In one embodiment, the driving ramp 300 furtherincludes contact surface 368 that engages the rim 332 of the headportion 324 of the actuator assembly 200. In the illustrated embodiment,the contact surface 368 has a generally annular shape.

In an embodiment, the driving ramp 300 further includes side portions360, 362 that extend from the upper portion 354 connecting the upperportion 354 with the lower portion 364 of the driving ramp 300. In anexemplary embodiment, the side portions 360, 362 of the driving ramp 300each include a ramped portion 438. In the illustrated embodiment, theramped portion 438 faces central ramp 300. In an embodiment, the rampedportion 438 is configured and dimensioned to engage the ramped portions306, 308 at the first end 39 of the second endplate 16. In oneembodiment, angled grooves 440 are formed in the ramped portions 316,318. In an exemplary embodiment, the angled grooves 440 are sized toreceive the corresponding tongues 316, 318 in the second endplate 16.Although the device 10 is described with tongues 316, 318 on the secondendplate 16 and angled grooves 440 on the driving ramp 300, it should beunderstood that that device 10 can also be configured with grooves onthe second endplate 16 and tongues on the driving ramp 300, inaccordance with one embodiment of the present invention.

A method of installing the expandable fusion device 10 of FIGS. 50-57 isnow discussed in accordance with one embodiment of the presentinvention. Prior to insertion of the fusion device, the disc space maybe prepared as described above. The expandable fusion device 10 can thenbe inserted into and seated in the appropriate position in theintervertebral disc space. In an embodiment, the device 10 is assembledprior to insertion. The expandable fusion device 10 can be introducedinto the intervertebral space, with the end having the first end 408 ofthe central ramp 18 being inserted. In an exemplary method, the fusiondevice 10 is in the unexpanded position when introduced into theintervertebral space. In an exemplary method, the intervertebral spacemay be distracted prior to insertion of the fusion device 10. Thedistraction provide some benefits by providing greater access to thesurgical site making removal of the intervertebral disc easier andmaking scraping of the endplates of the vertebral bodies 2, 3 easier.

With the fusion device 10 inserted into and seated in the appropriateposition in the intervertebral disc space, the fusion device can thenexpand into the expanded position. To expand the fusion device 10, aninstrument is engaged with the head portion 324 of the actuator assembly200. The instrument is used to rotate actuator assembly 200. Asdiscussed above, actuator assembly 200 is threadingly engaged with therod receiving extension 416 of the central ramp 18; thus, as theactuator assembly 200 is rotated in a first direction, the central ramp18 is pulled toward the actuator assembly 200. In an exemplaryembodiment, the actuator assembly 200 is moved in a linear directionwith the ratchet teeth engaging as means for controlling the movement ofthe actuator assembly 200 and the central ramp 18.

As the central ramp 18 is pulled towards the actuator assembly 200, thecentral ramp 18 acts to push endplates 14, 16 outwardly into theexpanded position. By way of example, the first ramped portions 424,second ramped portions 426, and central ramped portions 432 push againstthe corresponding ramped portions in the first and second endplates 14,16. The first ramped portions 424 in the first expansion portion 412 ofthe central ramp 18 push against the second ramped portions 310, 312 ofthe second endplate 16 with the corresponding tongues 320, 322 in thesecond ramped portions 310, 312 of the second endplate 16 riding inangled grooves 428 in the first ramped portions 424 in the firstexpansion portion 412. The second ramped portions 426 in the firstexpansion portion 412 push against the first ramped portions 316, 318 ofthe first endplate 14 with the corresponding tongues 316, 318 in firstramped portions 316, 318 of the first endplate 14 riding in angledgrooves 430 in the second ramped portions 426 in the first expansionportion 412. The central ramped portions 432 in the second expansionportion 414 push against the central ramped portion 402 in the first andsecond endplates 14, 16.

As discussed above, the actuator assembly 200 also engages driving ramp300; thus, as the actuator assembly 200 is rotated in a first direction,the actuator assembly 200 pushes the driving ramp 300 towards thecentral ramp 18 in a linear direction. As the driving ramp 300 is pushedtowards the central ramp 18, the driving ramp 300 also acts to push theendplates 14, 16 outwardly into the expanded position. By way ofexample, the ramped portions 438 of the driving ramp 300 push againstramped portions 306, 308 at the first end 39 of the second endplate 16.As the endplates 14, 16 move outwardly, the tongues 316, 318 in theramped portions 306, 308 of the second endplate 16 ride in the angledgrooves 440 in the ramped portions 438 of the driving ramp 300.

It should also be noted that the expansion of the endplates 14, 16 canbe varied based on the differences in the dimensions of the variousramped portions in the central ramp 18, the driving ramp 300, and thefirst and second endplates 14, 16. As best seen in FIG. 16, theendplates 14, 16 can be expanded in any of the following ways: straightrise expansion, straight rise expansion followed by a toggle into alordotic expanded configuration, or a phase off straight rise into alordotic expanded configuration.

In the event the fusion device 10 needs to be repositioned or revisedafter being installed and expanded, the fusion device 10 can becontracted back to the unexpanded configuration, repositioned, andexpanded again once the desired positioning is achieved. To contract thefusion device 10, the instrument can be used to rotate the actuatorassembly 200 in a second direction that is opposite the first direction.Rotation of the actuator assembly 200 results in movement of the centralramp 18 and the driving ramp 300 away from one another. As the centralramp 18 and the driving ramp 300 move, the endplates 14, 16 moveinwardly into the unexpanded position.

Referring now to FIGS. 58-63, an alternative embodiment of theexpandable fusion device 10 is shown. In the illustrated embodiment, thefusion device 10 includes a first endplate 14, a second endplate 16, acentral ramp 18, an actuator assembly 200, and a driving ramp 300. In anembodiment, the actuator assembly 200 functions to pull the central ramp18 and the driving ramp 300 together, which forces apart the first andsecond endplates 14, 16. In an embodiment, the expandable fusion devicemay contain features, such as a through bore, that facilitate placementdown an endoscopic tube. In an embodiment, the assembled fusion device10 may be placed down the endoscopic tube and then expanded.

The first endplates 14, 16 of the expandable fusion device 10 shown onFIGS. 58-63 may be similar to those described above with respect to theembodiment of FIGS. 50-57. As illustrated, the first endplate 14 maycomprise a first or front end 39 and a second or rear end 41 with firstand second side portions 202, 204 connecting the first end 39 and thesecond end 41. It should understood that references to the front andrear of the expandable fusion device 10 or a particular componentthereof, such as the first endplate 14, is with respect to the directionof placement into an intervertebral disc space with the front of thedevice 10 or particular component thereof being placed into the spacefirst followed by the rear of the device 10 or particular componentthereof. The first endplate 14 further comprises first or front rampedportions 306 a, 308 a on the first and second side portions 202, 204,respectively, proximate the first end 39 of the endplate 14. The firstendplate 14 further comprises second or rear ramped portions 310 a, 312a on the first and second side portions 202, 204, respectively,proximate the second end 41 of the endplate 14. The first endplate 14further comprises central ramped portion 402 a on the second sideportion 204. The second endplate 16 also contains corresponding firstramped portions 306 b, 308 b, second ramped portions 310 b, 312 b, andcentral ramped portion 402 b.

To achieve a greater degree of expansion, embodiments of the presentinvention may be designed with overlapping of the first and secondendplates 14, 16. By having overlap of the first and second endplates14, 16, a more compact design may be achieved for the expandable fusiondevice 10 when in an unexpanded position (e.g., FIGS. 59 and 62), whichin turn allows for a greater height when placed into an expandedposition (e.g., FIGS. 60 and 61). In some embodiments, one or more ofthe first ramped portions 306 a, 308 a at the first end 39 of the firstendplate 14 overlap one or more of the first ramped portions 306 b, 308b at the first end 39 of the second endplate 16. As best seen on FIG.63, the first ramped portion 306 a of the first endplate 14 overlaps thefirst ramped portion 306 b of the second endplate 16, and the firstramped portion 308 b of the second endplate 16 overlaps the first rampedportion 308 a of the first endplate 14. In some embodiments, one or moreof the second ramped portions 310 a, 312 a at the second end 41 of thefirst endplate 14 overlap one or more of the second ramped portions 310b, 312 b at the second end 41 of the second endplate 16. As best seen onFIG. 63, the first ramped portion 312 a of the first endplate 14overlaps the first ramped portion 312 b of the second endplate 16, andthe first ramped portion 310 b of the second endplate 16 overlaps thefirst ramped portion 310 a of the first endplate 14.

The actuator assembly 200 of the expandable fusion device 10 shown onFIGS. 58-63 may be similar to those described above with respect to theembodiment of FIGS. 50-57. With reference to FIGS. 58 and 61-62, theactuator assembly 200 includes a head portion 324 and an extension 404.The actuator assembly 200 further includes first and second locks rings450, 452 and washer 454. The first and second lock rings 450, 452 aid insecuring the actuator assembly 200 to the driving ramp 300, thuspreventing back-out of the actuator assembly 200 from the driving ramp300 when the actuator assembly 200 is rotated, for example. The secondlock ring 452 is configured to assembled with an interference fit toprevent undesired actuator assembly rotation.

The central ramp 18 of the expandable fusion device 10 shown on FIGS.58-63 may be similar to the central ramp 18 described above with respectto the embodiment of FIGS. 50-57. With reference to FIGS. 58 and 62-62,the central ramp 18 has a first or front end 408 and a second or rearend 410. In the illustrated embodiment, the central ramp 18 includes anexpansion portion 412 proximate the first end 408 and a rod-receivingextension 416 extending longitudinally from the expansion portion 412.As best seen on FIG. 58, the expansion portion 412 may include a firstramped portion 456 and a second ramped portion 458 that extend inoblique directions with respect to the longitudinal axis of theexpandable fusion device 10. The first ramped portion 456 may faceupward and toward the rear of the expandable fusion device 10 while thesecond ramped portion 458 may face downward and toward the rear of theexpandable fusion device 10.

The rod-receiving extension 416 extends from the expansion portion 412and has an opening 434 at the second end 410 of the central ramp 18. Inan embodiment, the rod-receiving extension 416 is sized and configuredto receive the extension 404 of the actuator assembly 200. In anembodiment, the rod-receiving extension 416 has threading with therod-receiving extension 416 threadingly receiving extension 404 of theactuator assembly 200. In another embodiment, the rod-receivingextension 416 has ratchet teeth with the extension 404 being ratchetedinto the rod-receiving extension 416. As illustrated, the rod-receivingextension 416 includes one or more ramped portions 460 a, 460 b. As bestseen on FIG. 61, the ramped portion 460 a is positioned on an oppositeside of the extension 416 from ramped portion 460 a and projectsdownward and toward the rear. As best seen on FIG. 58, ramped portion460 b projects outward from the extension 416 and faces upward andtoward the rear of the expandable fusion device 10.

The rod-receiving extension 416 extends from the expansion portion 412and has an opening 434 at the second end 410 of the central ramp 18. Inan embodiment, the rod-receiving extension 416 is sized and configuredto receive the extension 404 of the actuator assembly 200. In anembodiment, the rod-receiving extension 416 has threading with therod-receiving extension 416 threadingly receiving extension 404 of theactuator assembly 200. In another embodiment, the rod-receivingextension 416 has ratchet teeth with the extension 404 being ratchetedinto the rod-receiving extension 416. As illustrated, the rod-receivingextension 416 includes one or more ramped portions 460 a, 460 b. As bestseen on FIG. 61, the ramped portion 460 a is positioned on an oppositeside of the extension 416 from ramped portion 460 a and projectsdownward and toward the rear. As best seen on FIG. 58, ramped portion460 b projects outward from the extension 416 and faces upward andtoward the rear of the expandable fusion device 10.

The driving ramp 300 of the expandable fusion device 10 shown on FIGS.58-63 may be similar to the central ramp 18 described above with respectto the embodiment of FIGS. 50-57. As best seen on FIG. 58, the drivingramp 300 may include side portions 360, 362 that extend from upperportion 354 connecting the upper portion 354 with the lower portion 364of the driving ramp 300. In an exemplary embodiment, the side portions360, 362 of the driving ramp 300 each include a ramped portion 438. Inthe illustrated embodiment, the ramped portion 438 faces central ramp300. In an embodiment, the ramped portion 438 is configured anddimensioned to engage the ramped portions 310 b, 312 b at the second end41 of the second endplate 16.

A method of installing the expandable fusion device 10 of FIGS. 58-63 isnow discussed in accordance with one embodiment of the presentinvention. Prior to insertion of the fusion device 10, the disc spacemay be prepared as described above. The expandable fusion device 10 canthen be inserted into and seated in the appropriate position in theintervertebral disc space. In an embodiment, the device 10 is assembledprior to insertion. The expandable fusion device 10 can be introducedinto the intervertebral space, with the front end having the first end408 of the central ramp 18 being inserted first. In an exemplary method,the fusion device 10 is in the unexpanded position when introduced intothe intervertebral space. In an exemplary method, the intervertebralspace may be distracted prior to insertion of the fusion device 10. Thedistraction provide some benefits by providing greater access to thesurgical site making removal of the intervertebral disc easier andmaking scraping of the endplates of the vertebral bodies 2, 3 easier.

With the fusion device 10 inserted into and seated in the appropriateposition in the intervertebral disc space, the fusion device 10 can thenexpand into the expanded position. To expand the fusion device 10, aninstrument is engaged with the head portion 324 of the actuator assembly200. The instrument is used to rotate actuator assembly 200. Asdiscussed above, actuator assembly 200 is threadingly engaged with therod receiving extension 416 of the central ramp 18; thus, as theactuator assembly 200 is rotated in a first direction, the central ramp18 is pulled toward the actuator assembly 200. In an exemplaryembodiment, the actuator assembly 200 is moved in a linear directionwith the ratchet teeth engaging as means for controlling the movement ofthe actuator assembly 200 and the central ramp 18.

As the central ramp 18 is pulled towards the actuator assembly 200, thecentral ramp 18 acts to push endplates 14, 16 outwardly into theexpanded position. By way of example, the first and second rampedportions 456, 458 and ramped portions 460 a, 460 b push against thecorresponding ramped portions in the first and second endplates 14, 16.The first ramped portion 416 in the expansion portion 412 of the centralramp 18 pushes against the first ramped portions 306 b, 308 b of thesecond endplate 16. The second ramped portion 458 in the expansionportion 412 pushes against the first ramped portions 306 a, 306 b of thefirst endplate 14. The central ramped portion 460 b projecting from therod-receiving extension 416 of the driving ramp 18 pushes against thecentral ramped portion 402 b in the second endplate 16 while the centralramped portion 460 a pushes against the central ramped portion 402 a inthe first endplate 14.

As discussed above, the actuator assembly 200 also engages driving ramp300; thus, as the actuator assembly 200 is rotated in a first direction,the actuator assembly 200 pushes the driving ramp 300 towards thecentral ramp 18 in a linear direction. As the driving ramp 300 is pushedtowards the central ramp 18, the driving ramp 300 also acts to push theendplates 14, 16 outwardly into the expanded position. By way ofexample, the ramped portions 438 of the driving ramp 300 push againstramped portions 310 a, 312 b at the second end 41 of the second endplate16.

It should also be noted that the expansion of the endplates 14, 16 canbe varied based on the differences in the dimensions of the variousramped portions in the central ramp 18, the driving ramp 300, and thefirst and second endplates 14, 16. As best seen in FIG. 16, theendplates 14, 16 can be expanded in any of the following ways: straightrise expansion, straight rise expansion followed by a toggle into alordotic expanded configuration, or a phase off straight rise into alordotic expanded configuration.

In the event the fusion device 10 needs to be repositioned or revisedafter being installed and expanded, the fusion device 10 can becontracted back to the unexpanded configuration, repositioned, andexpanded again once the desired positioning is achieved. To contract thefusion device 10, the instrument can be used to rotate the actuatorassembly 200 in a second direction that is opposite the first direction.Rotation of the actuator assembly 200 results in movement of the centralramp 18 and the driving ramp 300 away from one another. As the centralramp 18 and the driving ramp 300 move, the endplates 14, 16 moveinwardly into the unexpanded position.

Referring now to FIGS. 64-66, an alternative embodiment of theexpandable fusion device 10 is shown. As illustrated, the expandablefusion device 10 includes a first endplate 14, a second endplate 16, acentral ramp 18, an actuator assembly 200, and a driving ramp 300. Theexpandable fusion device 10 shown on FIGS. 64-66 is similar to theembodiment described above with respect to FIGS. 58-63, except therod-receiving extension 416 includes additional ramped portions 460 c,460 d projecting there from. In the illustrated embodiment, the centralramp 18 includes an extension portion 412 and a rod-receiving extension416 that extends longitudinally from the extension portion 412. Therod-receiving extension 416 includes ramped portions 460 a, 460 b, 460c, 460 d that project outward from the extension 416. As best seen inFIGS. 64 and 66, ramped portions 460 b, 460 d face upward and toward therear. Ramped portions 460 b, 460 d are configured to engagecorresponding central ramps 402 b, 402 d in the second endplate 16. Asbest see in FIGS. 64 and 66, ramped portions 460 a, 460 c face downwardand toward the rear. Ramped portions 460 a, 460 c are configured toengage corresponding central ramps 402 a, 402 c on the first endplate14. Ramped portions 460 b, 460 c are on an opposite side of theextension 416 from ramped portions 460 a, 460 d.

Referring now to FIG. 67, an alternative embodiment of the expandablefusion device 10 is shown. As illustrated, the expandable fusion device10 includes a first endplate 14, a second endplate 16, a central ramp18, an actuator assembly 200, and a driving ramp 300. The expandablefusion device 10 shown on FIG. 67 is similar to the embodiment describedabove with respect to FIGS. 64-66, except the rod-receiving extension416 includes a radial through opening or window 462. In exemplaryembodiments, the window 462 may be sized to receive bone graft orsimilar bone growth inducing material and allow bone graft or similarbone growth inducing material to be packed into the device 10. In someembodiments, the window 462 may align with through openings 464 a, 464 bin the first endplate 14 and second endplate 16, respectively.

As previously discussed, embodiments of the present invention mayinclude insertion of an expandable fusion device 10 into a disc space.In accordance with present embodiments, a number of differentinstruments may be used to form the access path leading through thepatient's tissue and into the disc space. In some embodiments, theseinstruments may be arranged with the expandable fusion device 10 in akit. These instruments may include, for example, needle assemblies, aKirschner wire (“k-wire”), dilators, cannulas, and/or cutting devices.The needle assemblies may be used for creation of the initial pathleading to the disc space, for example. An example of a suitable needleassembly includes a Jamshidi needle. In some instances, the needleassembly may include a stylet slidably disposed within a needle.Dilators may be placed over the k-wire and used to access the discspace, for example. In addition, dilators may also be used to enlargethe access path through the tissue created by the needle assembly.Cannulas may be used to provide a working channel into the disc space.Dilators and cannulas of different diameters may be provided. In someembodiments, the cannula may have a diameter of less than about 15 mmand, alternatively, less than about 10 mm. Cutting devices, such asintervertebral disc reamers, may be used to prepare the disc space, forexample, by partially or completely removing the intervertebral disc.

FIG. 68 illustrates a dilator 466 that may be used in accordance withone embodiment of the present invention. As illustrated, the dilator 466may have a proximal 468 and a distal end 470. In one particularembodiment, the dilator 466 may comprise an elongated, cylindrical body.In the illustrated embodiment, the distal end 470 of the dilator 466 istapered for penetrating soft tissue of the patient when twisted orpushed. The dilator 466 may have measured markings 472 along its length,for example, to gauge the depth of insertion.

FIG. 69 illustrates a cannula 474 in accordance with one embodiment ofthe present invention. As illustrated, the cannula 474 may have aproximal 476 and a distal end 478. In one particular embodiment, thecannula 474 may comprise an elongated, cylindrical body. The cannula 474may have measured markings 480 along its length, for example, to gaugethe depth of insertion. FIGS. 70-71 illustrate alternate embodiments ofthe cannula 474 in which the proximal end 476 of the cannula 474includes notches 482. The notches 482 allow connection of attachments tothe proximal end 476 of the cannula 474. As illustrated by FIG. 72, aconnection assembly 484, which may be in the general shape of a collar,may be fitted onto the end of the cannula 474. In some embodiment, afunnel 486 may be attached to the collar-shaped connection assembly 484.As shown by FIG. 73, a fluid adapter 488 for introducing fluids into thedisc space through the cannula 474 may be secured to the connectionassembly 484 in alternative embodiments. In some embodiments, the distalend 478 of the cannula 474 may contain one or more features forfacilitating insertion of the cannula 474 through adjacent vertebralbodies while avoiding the nerve root. For example, as shown by FIGS. 72and 73, the distal end 478 of the cannula 474 may have one or moreflattened outer surfaces 490 extending along a length of the cannula474. In some embodiments, the flattened outer surfaces 490 may be onopposite sides of the cannula 474. A dilator 466 (e.g., shown on FIG.68) for use with the cannula 474 of FIGS. 72 and 73 may be adapted, inaccordance with present embodiments, to also have correspondingflattened outer surfaces.

An example technique for endoscopically inserting an expandable fusiondevice 10 between adjacent vertebrae will now be described. Inaccordance with present embodiments, an access path to theintervertebral disc space may be created. In some embodiments, theaccess path may be created using a posterolateral approach. For example,the access path may be at an angle of about 45° from the posterior ofthe patient. The access path may be through Kambin's triangle in someembodiments. To create the access path, the spinal needle assemblycomprising a stylette and needle, for example, may be inserted into thepatient's tissue and advanced to the disc space. The stylette may now beremoved from the needle assembly with placement of the k-wire into thedisc space through the needle. A dilator may now be placed over thek-wire and advanced through the patient's tissue to impact the discspace. A working cannula may now be placed over the dilator and into thedisc space. A partial or complete discectomy may now be performedthrough the cannula. In some embodiment, an intervertebral disc reamermay be inserted through the cannula and manipulated to at leastpartially remove the disc. In some embodiment, the endplates of theadjacent vertebrae may be scraped to expose end surface for facilitatingbone growth across the intervertebral disc space. Bone graft or similarbone growth inducing material may then be introduced into the disc spacethrough the cannula. The working cannula may then be removed and atransition dilator may be advanced to the disc space. The transitiondilator may have a larger diameter than the working cannula. Next, animplant cannula may be inserted over the transition dilator. The implantcannula may be sized to receive the expandable fusion device 10. In someembodiments, the implant cannula may be placed over the dilator with thediscectomy performed through the implant cannula rather than the workingcannula. The expandable fusion device 10 may then be placed into thedisc space through the implant cannula and expanded to the desiredheight. Bone graft or similar bone growth inducing material may then beintroduced into the expandable fusion device 10 in the disc space. Insome embodiments, more than one access path to the disc space may becreated with one or more steps performed through each access path. Forexample, the discectomy may be performed though a first access pathwhile the fusion device 10 may be introduced through a second accesspath.

Although the preceding discussion only discussed having a singleexpandable fusion device Although the preceding discussion onlydiscussed having a single expandable fusion device 10 in theintervertebral space, it is contemplated that more than one fusiondevice 10 can be inserted in the intervertebral space. When more thanone fusion device 10 is used, each fusion device 10 may be introducedthrough the same or different access paths. It is further contemplatedthat each fusion device 10 does not have to be finally installed in thefully expanded configuration. Rather, depending on the location of thefusion device 10 in the intervertebral disc space, the height of thefusion device 10 may vary from unexpanded to fully expanded. It shouldbe noted that, as well as the height being varied from an unexpandedconfiguration to an expanded configuration, the fusion 10 may bepositioned permanently anywhere between the expanded configuration andthe unexpanded configuration. Even further, although the precedingdescription describes expansion of the first and second endplates 14, 16by pulling together of the central ramp 18 and the driving ramp (e.g.,driving ramp 300), it is contemplated that embodiments of the presentinvention may include an expandable fusion device 10 in which thecentral ramp 18 and the driving ramp 300 are pushed away from oneanother to facilitate expansion of the first and second endplates 14,16.

FIG. 74 is an exploded view of an alternative embodiment of anexpandable fusion device with a graft delivery hole in accordance withembodiments of the present invention. The fusion device 10 shares manysimilar features with prior embodiments, including a first endplate 14,a second endplate 16, a central ramp 18, a driving ramp 300 and anactuator assembly 200. However, the fusion device 10 in FIG. 74 alsoincludes additional features, including multiple through openings 44 a,44 b in the endplates and graft delivery holes 512, 515 in the rear ofthe driving ramp 300 and the central ramp 18.

The expandable fusion device 10 includes a first endplate 14 and asecond endplate 16. In some embodiments, the fusion device 10 caninclude a larger footprint than prior designs. In some embodiments, thefusion device 10 can be used in a lateral procedure, such as a lumbarlateral interbody fusion procedure, though one skilled in the art willappreciate that the device need not be limited to this approach. As thefusion device 10 in FIG. 74 can have a larger footprint, the endplates14, 16 can also accommodate multiple through openings 44 a, 44 b, whichare placed adjacent to one another. These openings 44 a, 44 badvantageously accommodate bone growth along the longitudinal length ofthe fusion device 10. In some embodiments, opening 44 a is the same sizeas opening 44 b. In other embodiments, opening 44 a is of a differentsize from opening 44 b.

Between the endplates 14 and 16 is the central ramp 18. The central ramp18 includes a first expansion portion 412 and multiple ramped/angledportions 460 a, 460 b, 460 c, 460 d that are configured to engage withadjacent ramped/angled surfaces of the endplates. In some embodiments,the central ramp 18 can include at least two ramped portions extendingfrom an upper surface and at least two ramped portions extending from alower surface of the central ramp 18. Two or more ramped portions can beseparated by a bridge member that extends along a longitudinal length ofthe central ramp 18. As shown in FIG. 74, in a rear portion of thecentral ramp 18, the central ramp 18 advantageously includes both athrough bore 418 and a graft delivery hole 515. In some embodiments, thethrough bore 418 is threaded and configured to receive the threadedextension 404 of the actuator assembly 200. In contrast to priorembodiments, the central longitudinal axis of the through bore 418 isoff-center from the central longitudinal axis of the central ramp 18 inorder to accommodate the graft delivery hole 515. The adjacent graftdelivery hole 515 advantageously serves as an access port to allow graftmaterial to be delivered through the central ramp 18, either prior toinsertion or even in situ if desired. The through bore 418 aligns withbore 366 in the driving ramp 300 and the graft delivery hole 515 alignswith an additional graft delivery hole 512 in the driving ramp 300, asdiscussed below. In addition, the central ramp 18 further includes afirst opening 520 a and a second opening 520 b that are in communicationwith through openings 44 a and 44 b on the endplates.

Adjacent the central ramp 18 is the driving ramp 300, which includes oneor more ramped portions 438. Like the central ramp 18, the driving ramp300 includes a bore 366 adjacent a graft delivery hole 512. The bore 366is configured to receive the actuator assembly 200 therethrough, and isaligned with the through bore 418 in the central ramp 18. Accordingly,the bore 366 has a central longitudinal axis that is off-set from thecentral longitudinal axis of the driving ramp 300 to accommodate theadjacent graft delivery hole 512. The graft delivery hole 512 of thedriving ramp 300 is aligned with the graft delivery hole 515 of thecentral ramp 18 to allow graft material to be inserted into the implant,either prior to or even after insertion of the implant.

The expandable fusion device 10 further includes an actuator assembly200 including a head portion 324 and a threaded shaft portion. Theactuator assembly 200 is configured for insertion through the bore 366in the driving ramp 300 and is operably coupled to the central ramp 18.As shown in FIG. 74, the actuator assembly 200 can include a lockingring 450 that is retained in a groove on the head portion 324 of theactuator assembly 200. Advantageously, as the head portion 324 of theactuator assembly 200 is inserted through the driving ramp 300, thelocking ring 450 can compress and then expand within the driving ramp300, thereby securely retaining the actuator assembly 200 in the drivingramp 300. In addition, the actuator assembly 200 can be accompanied by awasher 454. In some embodiments, the washer 454 can ride on the outsideof the head portion 324 of the actuator assembly 200. The washer 454 canadvantageously create a drag on the actuator assembly 200, therebyadvantageously preventing unnecessary rotation of the actuator assembly200 in the implant assembly.

FIGS. 75A and 75B are rear views of the expandable fusion device of FIG.74. FIG. 75A shows the expandable fusion device 10 in a contractedstate, while FIG. 75B shows the expandable fusion device 10 in anexpanded state. From this view, one can see the bore 366 alignedalongside the graft delivery hole 512. Both the bore 366 and the graftdelivery hole 512 are off-set from a central longitudinal axis of thedriving ramp 300.

FIG. 76 is a top view of the expandable fusion device of FIG. 74. Fromthis view, one can see the actuator assembly 200 offset from a centrallongitudinal axis of the entire implant. In addition, from this view,one can see how the endplate openings 44 a and 44 b are of differentsizes. By providing endplate openings 44 a and 44 b of different sizes,this advantageously allows graft material to be distributed differentlyalong different points of the longitudinal axis of the implant 10.

FIG. 77 shows a side view of the expandable fusion device of FIG. 74.From this view, one can see the interaction between the various ramps460 of the central ramp 18 with the ramped surfaces of the adjacentendplates 14, 16.

FIG. 78 is an exploded view of an alternative embodiment of anexpandable fusion device having removably attachable plates inaccordance with embodiments of the present invention. The fusion device10 shares many similar features with prior embodiments, including afirst endplate 14, a second endplate 16, a central ramp 18 with rampedsurfaces 460, a driving ramp 300 and an actuator assembly 200. However,the fusion device 10 in FIG. 78 also includes additional features,including an upper plate member 604 and a lower plate member 608 thatcan be removably attached to the first endplate 14 and second endplate16, respectively. The upper plate member 604 and the lower plate member608 are advantageously configured to receive a fastener or bone screw(as shown in FIG. 80) that can be inserted into adjacent vertebralbodies. Advantageously, with the addition of the upper plate member 604and the lower plate member 608, the fusion device 10 can be astand-alone fusion device, as the plate members 604, 608 provideadditional support to the device 10. In some embodiments, the upperplate member 604 and/or the lower plate member 608 can be removablydetachable from the remaining components of the fusion device. In otherembodiments, the upper plate member 604 and/or the lower plate member608 can be fixedly attached such that it is not removable or detachable.

The expandable fusion device 10 includes a first endplate 14 and asecond endplate 16. Like the embodiment in FIG. 74, the fusion device 10can include a larger footprint than other designs. In some embodiments,the fusion device 10 can be used in a lateral procedure, such as alumbar lateral interbody fusion procedure, though one skilled in the artwill appreciate that the device need not be limited to this approach. Asthe fusion device 10 in FIG. 78 can have a large footprint, theendplates 14, 16 can also accommodate multiple through openings 44 a, 44b, which are placed adjacent to one another. These openings 44 a, 44 badvantageously accommodate bone growth along the longitudinal length ofthe fusion device 10. In some embodiments, opening 44 a is the same sizeas opening 44 b. In other embodiments, opening 44 a is of a differentsize from opening 44 b.

As shown in FIG. 78, the first endplate 14 and second endplate 16 caninclude surface texturing, such as teeth, ribbing, grooves and ridgesthat assist in preventing expulsion of the device in between vertebralmembers. A raised surface 630 is formed at a rear portion of each of theendplates 14, 16 at the end of the surface texturing, as shown in FIGS.78 and 81. The raised surfaces 630 advantageously serve as a stop orlimit surface against which the upper plate member 604 and the lowerplate member 608 can abut against when attaching the plate members tothe endplates. As shown in FIG. 81, the raised surfaces 630 can betapered or angled such that they are not at an even height across thedevice 10. In addition to these features, the first endplate 14 and thesecond endplate 16 can include screw holes 630 for receiving screws 640to secure the endplates to the plate members.

Each of the first endplate 14 and the second endplate 16 can attach to aplate member. First endplate 14 can attach to upper plate member 604,while second endplate 16 can attach to lower plate member 608. In someembodiments, upper plate member 604 comprises an attachment portion 641comprising a groove or recess 642 that is configured to receive a ledge648 of the first endplate 14. Once the attachment portion 641 of theupper plate member 604 receives the first endplate 14 therein, one ormore set screws 640 can be delivered through the upper plate member 604and the first endplate 14 to easily secure the members together. In someembodiments, lower plate member 608 comprises an attachment portion 643comprising a groove 644 that is configured to receive a ledge 649 of thesecond endplate 16. Once the attachment portion 643 receives secondendplate 16 therein, one or more set screws 646 can be delivered throughthe lower plate member 608 and the second endplate 16 to easily securethe members together. In some embodiments, the upper plate member 604can be pinned to the first endplate 14 by a different means, while thelower plate member 608 can be pinned to the second endplate 16 by adifferent means.

Upper plate member 604 comprises a first opening 614 for receiving abone fastener 654 for inserting into an upper vertebral member, and asecond opening 612 for receiving a blocking set screw 621 for preventingback-out of the bone fastener 654 once the bone fastener 654 is insertedinto upper plate member 604. In some embodiments, blocking set screw 621can comprise a cut-out portion 660 (shown in FIG. 78) that allowspassage of the bone fastener 654 through the first opening 614. Once thebone fastener 654 passes through the first opening 614, the blocking setscrew 621 can be rotated to abut the head of the bone fastener 654,thereby preventing back-out of the bone fastener 654. Lower plate member608 comprises a first opening 618 for receiving a bone fastener 658 forinserting into a lower vertebral member, and a second opening 616 forreceiving a different blocking set screw 622 for preventing back-out ofthe bone fastener 658 once the bone fastener 658 is inserted into thelower plate member 608. In some embodiments, blocking set screw 622 cancomprise a cut-out portion 660 that allows passage of the bone fastener658 through the first opening 618. Once the bone fastener 658 passesthrough the first opening 618, the blocking set screw 622 can be rotatedto abut the head of the bone fastener 658, thereby preventing back-outof the bone fastener 658.

Advantageously, both the upper plate member 604 and the lower platemember 606 are optional. In some embodiments, a surgeon may choose toattach only one of the upper plate member 604 and the lower plate member606 to the device 10. In addition, both the upper plate member 604 andthe lower plate member 606 can be removably attached such that it ispossible to remove them if desired. Moreover, one skilled in the artwill appreciate that the upper plate member 604 and the lower platemember 606 need not be of the form as shown in FIG. 78. Other platemembers of different sizes and shapes can be attached to endplates,thereby advantageously providing a modular system that can accommodatedifferent patient anatomies.

Between the endplates 14 and 16 is the central ramp 18. The central ramp18 includes a first expansion portion 412 and multiple ramped/angledportions 460 a, 460 b, 460 c, 460 d that are configured to engage withadjacent ramped/angled surfaces of the endplates. As in the embodimentin FIG. 74, the central ramp 18 can include a through bore 418 adjacenta graft delivery hole 515. The central ramp 18 can attach to the drivingramp 300. The through bore 418 of the central ramp can align with a bore366 in the driving ramp, while the graft delivery hole 515 of thecentral ramp 18 can align with a graft delivery hole 512 in the drivingramp 300. In some embodiments, the graft delivery hole 515 can bethreaded. In addition, in some embodiments, the graft delivery hole 515can include a graft funnel attachment that can assist in deliveringmaterial through the graft delivery hole 515.

As in prior embodiments, an actuator assembly 200 can pass into thedriving ramp 300 and into the central ramp 18. The actuator assembly 200can be used to increase or decrease the height of the fusion device 10.

FIG. 79 is a side view of the fusion device 10 of FIG. 78 with platemembers attached to the endplates. From this view, one can see how theattachment portion 641 of the upper plate member 604 receives the ledge648 of the first endplate 14 and how the attachment portion 643 of thelower plate member 608 receives the ledge 649 of the second endplate 16.

FIG. 80 is a top perspective view of the fusion device 10 of FIG. 78 inan expanded state. As shown in this embodiment, expansion of the firstendplate 14 away from the second endplate 16 also causes expansion ofthe upper plate member 604 away from the lower plate member 608.

FIG. 81 is a rear view of the fusion device 10 of FIG. 78. From thisview, one can see the raised surface 630 a formed in the first endplateand the raised surface 630 b formed in the second endplate, which can beabutted against by plate members attached thereto.

FIGS. 82A and 82B are rear views of alternative expandable fusiondevices having different attachable plates in accordance withembodiments of the present invention. FIG. 82A shows a first upper platemember 604 a and a first upper plate member 608 a, each having aparticular orientation. FIG. 82B shows a second upper plate member 604 band a second upper plate member 608 b, each having a particularorientation. As the plate members 604 and 608 are modular and removablyattachable, a surgeon can advantageously choose amongst different platemembers with different orientations to attach to various patients,according to their anatomical differences.

The invention being thus described, it will be obvious that the same maybe varied in many ways. Such variations are not to be regarded as adeparture from the spirit and scope of the invention, and all suchmodifications as would be obvious to one skilled in the art are intendedto be included within the scope of the following claims. Althoughindividual embodiments are discussed, the invention covers allcombinations of all those embodiments.

What is claimed is:
 1. An expandable intervertebral implant, theexpandable implant capable of moving from a collapsed position to anexpanded position, the expandable implant comprising: a first endplateextending from a proximal end to a distal end, wherein the firstendplate has a first surface, a second surface, a first side surface anda second side surface; a second endplate extending from a proximal endto a distal end, wherein the second endplate has a first surface, asecond surface, a first side surface and a second side surface; acentral ramp positioned between the first endplate and the secondendplate, the central ramp positioned proximate the distal end of thefirst endplate and the distal end of the second endplate; a driving ramppositioned proximate the proximal end of the first endplate and theproximal end of the second endplate, wherein the driving ramp isoperably connected with the central ramp; an actuator assemblyconfigured to move at least one of the central ramp and the drivingramp; wherein the expandable implant defines a horizontal plane thatextends through the central ramp, driving ramp and the actuatorassembly; wherein the first side surface of the first endplate includesat least one ramped portion, wherein the first side surface of thesecond endplate includes at least one ramped portion, wherein in thecollapsed position, the at least one ramped portion of the first side ofthe first endplate extends through the horizontal plane such that the atleast one ramped portion of the first endplate is positioned on bothsides of the horizontal plane.
 2. The expandable implant of claim 1,wherein the second side surface of the first endplate includes at leastone ramped portion, wherein the second side surface of the secondendplate includes at least one ramped portion, wherein in the collapsedposition, the at least one ramped portion of the second side surface ofthe second endplate extends through the horizontal plane such that theat least one ramped portion of the second side surface of the secondendplate is positioned on both sides of the horizontal plane.
 3. Theexpandable implant of claim 1, wherein at least one of the central rampand the driving ramp is configured to move in a first direction andcause the first and second endplates to move away from one another. 4.The expandable implant of claim 1, wherein the central ramp comprises anextension, the extension including a threaded opening.
 5. The expandableimplant of claim 4, wherein the actuator assembly extends through anunthreaded opening in the driving ramp and extends into the threadedopening in the extension of the central ramp.
 6. The expandable implantof claim 1, wherein the actuator assembly comprises a head portion, athreaded portion and a connecting portion that connects the head portionand the threaded portion.
 7. The expandable implant of claim 1, whereinthe actuator assembly is configured for rotation in a first direction tomove at least one of the central ramp and the driving ramp causing thefirst and second endplates to move away from each other, and wherein theactuator assembly is configured for rotation in a second direction tomove at least one of the central ramp and the driving ramp causing thefirst and second endplates to move towards each other.
 8. The expandableimplant of claim 1, wherein the driving ramp includes an openingconfigured and dimensioned as a graft delivery opening to allow forgraft to be introduced into the expandable implant.
 9. The expandableimplant of claim 1, wherein the driving ramp has a first ramped surfaceand a second ramped surface, the first ramped surface is configured forengaging a portion of the first endplate and the second ramped surfaceis configured for engaging a portion of the second endplate, and whereinthe central ramp has a first ramped surface and a second ramped surface,the first ramped surface is configured for engaging a portion of thefirst endplate and the second ramped surface is configured for engaginga portion of the second endplate.
 10. An expandable intervertebralimplant, the expandable implant capable of moving from a collapsedposition to an expanded position, the implant comprising: a firstendplate extending from a proximal end to a distal end, wherein thefirst endplate has a first surface, a second surface, a first sidesurface and a second side surface; a second endplate extending from aproximal end to a distal end, wherein the second endplate has a firstsurface, a second surface, a first side surface and a second sidesurface; a central ramp positioned between the first endplate and thesecond endplate, the central ramp positioned proximate the distal end ofthe first endplate and the distal end of the second endplate; a drivingramp positioned proximate the proximal end of the first endplate and theproximal end of the second endplate, wherein the driving ramp isoperably connected with the central ramp; an actuator assemblyconfigured to move at least one of the central ramp and the drivingramp; wherein the first side surface of the first endplate includes atleast one ramped portion having an inwardly facing surface and anoutwardly facing surface, wherein the first side surface of the secondendplate includes an inwardly facing surface and an outwardly facingsurface, and wherein in the collapsed position, at least a portion ofthe inwardly facing surface of the ramped portion of the first endplateoverlaps at least a portion of the outwardly facing surface of the firstside surface of the second endplate.
 11. The expandable implant of claim10, wherein in the expanded position, at least a portion of the inwardlyfacing surface of the ramped portion of the first endplate is spacedfrom and does not overlap the outwardly facing surface of the first sidesurface of the second endplate.
 12. The expandable implant of claim 10,wherein the second side surface of the second endplate includes at leastone ramped portion having an inwardly facing surface and an outwardlyfacing surface, wherein the second side surface of the first endplateincludes an inwardly facing surface and an outwardly facing surface, andwherein in the collapsed position, at least a portion of the inwardlyfacing surface of the ramped portion of the second endplate overlaps atleast a portion of the outwardly facing surface of the second sidesurface of the first endplate.
 13. The expandable implant of claim 12,wherein in the expanded position, at least a portion of the inwardlyfacing surface of the ramped portion of the second endplate is spacedfrom and does not overlap the outwardly facing surface of the secondside surface of the first endplate.
 14. The expandable implant of claim10, wherein at least one of the central ramp and the driving ramp isconfigured to move in a first direction and cause the first and secondendplates to move away from one another.
 15. The expandable implant ofclaim 10, wherein the central ramp comprises an extension, the extensionincluding a threaded opening.
 16. The expandable implant of claim 15,wherein the actuator assembly extends through an unthreaded opening inthe driving ramp and extends into the threaded opening in the extensionof the central ramp.
 17. The expandable implant of claim 10, wherein thedriving ramp has a first ramped surface and a second ramped surface, thefirst ramped surface is configured for engaging a portion of the firstendplate and the second ramped surface is configured for engaging aportion of the second endplate, and wherein the central ramp has a firstramped surface and a second ramped surface, the first ramped surface isconfigured for engaging a portion of the first endplate and the secondramped surface is configured for engaging a portion of the secondendplate.
 18. The expandable implant of claim 10, wherein the actuatorassembly comprises a head portion, a threaded portion and a connectingportion that connects the head portion and the threaded portion.
 19. Theexpandable implant of claim 18, wherein the head portion of the actuatorassembly is captured in the driving ramp such that the head portion ofthe actuator assembly can rotate with respect to the driving ramp but istranslationally fixed with respect to the driving ramp.
 20. Theexpandable implant of claim 10, wherein the actuator assembly isconfigured for rotation in a first direction to move at least one of thecentral ramp and the driving ramp causing the first and second endplatesto move away from each other, and wherein the actuator assembly isconfigured for rotation in a second direction to move at least one ofthe central ramp and the driving ramp causing the first and secondendplates to move towards each other.